Gecko [ gandhischool.edu.np ]

Name	Size	Permission
utils	[ DIR ]	dr-xr-xr-x
accessor-pairs.js	11.71 KB	-rw-rw-rw-
array-bracket-newline.js	9.45 KB	-rw-rw-rw-
array-bracket-spacing.js	8.96 KB	-rw-rw-rw-
array-callback-return.js	15.5 KB	-rw-rw-rw-
array-element-newline.js	10.9 KB	-rw-rw-rw-
arrow-body-style.js	12.67 KB	-rw-rw-rw-
arrow-parens.js	7.61 KB	-rw-rw-rw-
arrow-spacing.js	5.17 KB	-rw-rw-rw-
block-scoped-var.js	4.24 KB	-rw-rw-rw-
block-spacing.js	5.8 KB	-rw-rw-rw-
brace-style.js	8.04 KB	-rw-rw-rw-
callback-return.js	6.41 KB	-rw-rw-rw-
camelcase.js	13.66 KB	-rw-rw-rw-
capitalized-comments.js	10.48 KB	-rw-rw-rw-
class-methods-use-this.js	6.02 KB	-rw-rw-rw-
comma-dangle.js	13.53 KB	-rw-rw-rw-
comma-spacing.js	6.87 KB	-rw-rw-rw-
comma-style.js	11.72 KB	-rw-rw-rw-
complexity.js	5.6 KB	-rw-rw-rw-
computed-property-spacing.js	7.45 KB	-rw-rw-rw-
consistent-return.js	6.91 KB	-rw-rw-rw-
consistent-this.js	4.99 KB	-rw-rw-rw-
constructor-super.js	15.19 KB	-rw-rw-rw-
curly.js	18.93 KB	-rw-rw-rw-
default-case-last.js	1.21 KB	-rw-rw-rw-
default-case.js	2.77 KB	-rw-rw-rw-
default-param-last.js	1.55 KB	-rw-rw-rw-
dot-location.js	3.43 KB	-rw-rw-rw-
dot-notation.js	6.6 KB	-rw-rw-rw-
eol-last.js	4.01 KB	-rw-rw-rw-
eqeqeq.js	5.65 KB	-rw-rw-rw-
for-direction.js	5 KB	-rw-rw-rw-
func-call-spacing.js	9.77 KB	-rw-rw-rw-
func-name-matching.js	9.91 KB	-rw-rw-rw-
func-names.js	6.3 KB	-rw-rw-rw-
func-style.js	2.85 KB	-rw-rw-rw-
function-call-argument-newline...	4.31 KB	-rw-rw-rw-
function-paren-newline.js	11.61 KB	-rw-rw-rw-
generator-star-spacing.js	7.01 KB	-rw-rw-rw-
getter-return.js	6.87 KB	-rw-rw-rw-
global-require.js	2.44 KB	-rw-rw-rw-
grouped-accessor-pairs.js	7.46 KB	-rw-rw-rw-
guard-for-in.js	2.31 KB	-rw-rw-rw-
handle-callback-err.js	3.06 KB	-rw-rw-rw-
id-blacklist.js	7.54 KB	-rw-rw-rw-
id-denylist.js	7.04 KB	-rw-rw-rw-
id-length.js	6.51 KB	-rw-rw-rw-
id-match.js	11.04 KB	-rw-rw-rw-
implicit-arrow-linebreak.js	2.88 KB	-rw-rw-rw-
indent-legacy.js	43.59 KB	-rw-rw-rw-
indent.js	76.54 KB	-rw-rw-rw-
index.js	17.89 KB	-rw-rw-rw-
init-declarations.js	4.38 KB	-rw-rw-rw-
jsx-quotes.js	2.98 KB	-rw-rw-rw-
key-spacing.js	26.36 KB	-rw-rw-rw-
keyword-spacing.js	23.7 KB	-rw-rw-rw-
line-comment-position.js	4.09 KB	-rw-rw-rw-
linebreak-style.js	3.48 KB	-rw-rw-rw-
lines-around-comment.js	17.85 KB	-rw-rw-rw-
lines-around-directive.js	7.6 KB	-rw-rw-rw-
lines-between-class-members.js	11.15 KB	-rw-rw-rw-
logical-assignment-operators.j...	21.38 KB	-rw-rw-rw-
max-classes-per-file.js	2.58 KB	-rw-rw-rw-
max-depth.js	4.68 KB	-rw-rw-rw-
max-len.js	15.81 KB	-rw-rw-rw-
max-lines-per-function.js	6.92 KB	-rw-rw-rw-
max-lines.js	5.95 KB	-rw-rw-rw-
max-nested-callbacks.js	3.48 KB	-rw-rw-rw-
max-params.js	3.1 KB	-rw-rw-rw-
max-statements-per-line.js	7.35 KB	-rw-rw-rw-
max-statements.js	5.81 KB	-rw-rw-rw-
multiline-comment-style.js	21.22 KB	-rw-rw-rw-
multiline-ternary.js	7.62 KB	-rw-rw-rw-
new-cap.js	9.3 KB	-rw-rw-rw-
new-parens.js	3.19 KB	-rw-rw-rw-
newline-after-var.js	9.46 KB	-rw-rw-rw-
newline-before-return.js	7.87 KB	-rw-rw-rw-
newline-per-chained-call.js	4.04 KB	-rw-rw-rw-
no-alert.js	4.25 KB	-rw-rw-rw-
no-array-constructor.js	4.38 KB	-rw-rw-rw-
no-async-promise-executor.js	1.11 KB	-rw-rw-rw-
no-await-in-loop.js	2.73 KB	-rw-rw-rw-
no-bitwise.js	3.5 KB	-rw-rw-rw-
no-buffer-constructor.js	1.4 KB	-rw-rw-rw-
no-caller.js	1.18 KB	-rw-rw-rw-
no-case-declarations.js	1.83 KB	-rw-rw-rw-
no-catch-shadow.js	2.51 KB	-rw-rw-rw-
no-class-assign.js	1.73 KB	-rw-rw-rw-
no-compare-neg-zero.js	1.9 KB	-rw-rw-rw-
no-cond-assign.js	5.52 KB	-rw-rw-rw-
no-confusing-arrow.js	2.9 KB	-rw-rw-rw-
no-console.js	7.17 KB	-rw-rw-rw-
no-const-assign.js	1.52 KB	-rw-rw-rw-
no-constant-binary-expression....	20.41 KB	-rw-rw-rw-
no-constant-condition.js	4.77 KB	-rw-rw-rw-
no-constructor-return.js	1.57 KB	-rw-rw-rw-
no-continue.js	886 B	-rw-rw-rw-
no-control-regex.js	4.58 KB	-rw-rw-rw-
no-debugger.js	959 B	-rw-rw-rw-
no-delete-var.js	983 B	-rw-rw-rw-
no-div-regex.js	1.42 KB	-rw-rw-rw-
no-dupe-args.js	2.36 KB	-rw-rw-rw-
no-dupe-class-members.js	3.29 KB	-rw-rw-rw-
no-dupe-else-if.js	4.51 KB	-rw-rw-rw-
no-dupe-keys.js	3.88 KB	-rw-rw-rw-
no-duplicate-case.js	2.04 KB	-rw-rw-rw-
no-duplicate-imports.js	9.28 KB	-rw-rw-rw-
no-else-return.js	15.71 KB	-rw-rw-rw-
no-empty-character-class.js	2.23 KB	-rw-rw-rw-
no-empty-function.js	4.63 KB	-rw-rw-rw-
no-empty-pattern.js	2.38 KB	-rw-rw-rw-
no-empty-static-block.js	1.22 KB	-rw-rw-rw-
no-empty.js	3.08 KB	-rw-rw-rw-
no-eq-null.js	1.22 KB	-rw-rw-rw-
no-eval.js	9.34 KB	-rw-rw-rw-
no-ex-assign.js	1.43 KB	-rw-rw-rw-
no-extend-native.js	6.5 KB	-rw-rw-rw-
no-extra-bind.js	7.39 KB	-rw-rw-rw-
no-extra-boolean-cast.js	11.7 KB	-rw-rw-rw-
no-extra-label.js	5.04 KB	-rw-rw-rw-
no-extra-parens.js	52.03 KB	-rw-rw-rw-
no-extra-semi.js	4.99 KB	-rw-rw-rw-
no-fallthrough.js	6.89 KB	-rw-rw-rw-
no-floating-decimal.js	2.42 KB	-rw-rw-rw-
no-func-assign.js	2.2 KB	-rw-rw-rw-
no-global-assign.js	2.97 KB	-rw-rw-rw-
no-implicit-coercion.js	12.97 KB	-rw-rw-rw-
no-implicit-globals.js	5.48 KB	-rw-rw-rw-
no-implied-eval.js	4.54 KB	-rw-rw-rw-
no-import-assign.js	7.25 KB	-rw-rw-rw-
no-inline-comments.js	3.29 KB	-rw-rw-rw-
no-inner-declarations.js	2.96 KB	-rw-rw-rw-
no-invalid-regexp.js	6.3 KB	-rw-rw-rw-
no-invalid-this.js	5.01 KB	-rw-rw-rw-
no-irregular-whitespace.js	9.93 KB	-rw-rw-rw-
no-iterator.js	1.28 KB	-rw-rw-rw-
no-label-var.js	2.36 KB	-rw-rw-rw-
no-labels.js	4.38 KB	-rw-rw-rw-
no-lone-blocks.js	4.23 KB	-rw-rw-rw-
no-lonely-if.js	3.65 KB	-rw-rw-rw-
no-loop-func.js	6.16 KB	-rw-rw-rw-
no-loss-of-precision.js	8.07 KB	-rw-rw-rw-
no-magic-numbers.js	9.26 KB	-rw-rw-rw-
no-misleading-character-class....	9.87 KB	-rw-rw-rw-
no-mixed-operators.js	7.58 KB	-rw-rw-rw-
no-mixed-requires.js	7.26 KB	-rw-rw-rw-
no-mixed-spaces-and-tabs.js	3.67 KB	-rw-rw-rw-
no-multi-assign.js	1.76 KB	-rw-rw-rw-
no-multi-spaces.js	5.04 KB	-rw-rw-rw-
no-multi-str.js	1.8 KB	-rw-rw-rw-
no-multiple-empty-lines.js	6.25 KB	-rw-rw-rw-
no-native-reassign.js	2.99 KB	-rw-rw-rw-
no-negated-condition.js	2.9 KB	-rw-rw-rw-
no-negated-in-lhs.js	1.16 KB	-rw-rw-rw-
no-nested-ternary.js	1.12 KB	-rw-rw-rw-
no-new-func.js	2.98 KB	-rw-rw-rw-
no-new-native-nonconstructor.j...	2.11 KB	-rw-rw-rw-
no-new-object.js	1.72 KB	-rw-rw-rw-
no-new-require.js	1.17 KB	-rw-rw-rw-
no-new-symbol.js	1.58 KB	-rw-rw-rw-
no-new-wrappers.js	1.7 KB	-rw-rw-rw-
no-new.js	1.04 KB	-rw-rw-rw-
no-nonoctal-decimal-escape.js	5.47 KB	-rw-rw-rw-
no-obj-calls.js	2.7 KB	-rw-rw-rw-
no-object-constructor.js	3.55 KB	-rw-rw-rw-
no-octal-escape.js	1.44 KB	-rw-rw-rw-
no-octal.js	1.01 KB	-rw-rw-rw-
no-param-reassign.js	8.42 KB	-rw-rw-rw-
no-path-concat.js	1.68 KB	-rw-rw-rw-
no-plusplus.js	3.1 KB	-rw-rw-rw-
no-process-env.js	1.19 KB	-rw-rw-rw-
no-process-exit.js	1.24 KB	-rw-rw-rw-
no-promise-executor-return.js	8.54 KB	-rw-rw-rw-
no-proto.js	1.21 KB	-rw-rw-rw-
no-prototype-builtins.js	5.83 KB	-rw-rw-rw-
no-redeclare.js	5.67 KB	-rw-rw-rw-
no-regex-spaces.js	6.42 KB	-rw-rw-rw-
no-restricted-exports.js	7.1 KB	-rw-rw-rw-
no-restricted-globals.js	3.79 KB	-rw-rw-rw-
no-restricted-imports.js	16.6 KB	-rw-rw-rw-
no-restricted-modules.js	6.9 KB	-rw-rw-rw-
no-restricted-properties.js	6.17 KB	-rw-rw-rw-
no-restricted-syntax.js	2.17 KB	-rw-rw-rw-
no-return-assign.js	2.62 KB	-rw-rw-rw-
no-return-await.js	5.02 KB	-rw-rw-rw-
no-script-url.js	1.72 KB	-rw-rw-rw-
no-self-assign.js	5.5 KB	-rw-rw-rw-
no-self-compare.js	1.81 KB	-rw-rw-rw-
no-sequences.js	4.67 KB	-rw-rw-rw-
no-setter-return.js	7.07 KB	-rw-rw-rw-
no-shadow-restricted-names.js	2.16 KB	-rw-rw-rw-
no-shadow.js	12.31 KB	-rw-rw-rw-
no-spaced-func.js	2.42 KB	-rw-rw-rw-
no-sparse-arrays.js	1.17 KB	-rw-rw-rw-
no-sync.js	1.65 KB	-rw-rw-rw-
no-tabs.js	2.45 KB	-rw-rw-rw-
no-template-curly-in-string.js	1.15 KB	-rw-rw-rw-
no-ternary.js	889 B	-rw-rw-rw-
no-this-before-super.js	10.87 KB	-rw-rw-rw-
no-throw-literal.js	1.28 KB	-rw-rw-rw-
no-trailing-spaces.js	6.72 KB	-rw-rw-rw-
no-undef-init.js	2.35 KB	-rw-rw-rw-
no-undef.js	2.3 KB	-rw-rw-rw-
no-undefined.js	2.24 KB	-rw-rw-rw-
no-underscore-dangle.js	12.79 KB	-rw-rw-rw-
no-unexpected-multiline.js	4.19 KB	-rw-rw-rw-
no-unmodified-loop-condition.j...	11.65 KB	-rw-rw-rw-
no-unneeded-ternary.js	6.79 KB	-rw-rw-rw-
no-unreachable-loop.js	5.94 KB	-rw-rw-rw-
no-unreachable.js	8.9 KB	-rw-rw-rw-
no-unsafe-finally.js	3.91 KB	-rw-rw-rw-
no-unsafe-negation.js	4.63 KB	-rw-rw-rw-
no-unsafe-optional-chaining.js	6.97 KB	-rw-rw-rw-
no-unused-expressions.js	6.08 KB	-rw-rw-rw-
no-unused-labels.js	4.55 KB	-rw-rw-rw-
no-unused-private-class-member...	7.68 KB	-rw-rw-rw-
no-unused-vars.js	27 KB	-rw-rw-rw-
no-use-before-define.js	10.88 KB	-rw-rw-rw-
no-useless-backreference.js	7.57 KB	-rw-rw-rw-
no-useless-call.js	2.99 KB	-rw-rw-rw-
no-useless-catch.js	1.71 KB	-rw-rw-rw-
no-useless-computed-key.js	6.3 KB	-rw-rw-rw-
no-useless-concat.js	3.24 KB	-rw-rw-rw-
no-useless-constructor.js	5.75 KB	-rw-rw-rw-
no-useless-escape.js	13.18 KB	-rw-rw-rw-
no-useless-rename.js	5.88 KB	-rw-rw-rw-
no-useless-return.js	14.01 KB	-rw-rw-rw-
no-var.js	12.14 KB	-rw-rw-rw-
no-void.js	1.72 KB	-rw-rw-rw-
no-warning-comments.js	7.12 KB	-rw-rw-rw-
no-whitespace-before-property....	3.92 KB	-rw-rw-rw-
no-with.js	876 B	-rw-rw-rw-
nonblock-statement-body-positi...	4.56 KB	-rw-rw-rw-
object-curly-newline.js	11.53 KB	-rw-rw-rw-
object-curly-spacing.js	11.61 KB	-rw-rw-rw-
object-property-newline.js	3.8 KB	-rw-rw-rw-
object-shorthand.js	21.78 KB	-rw-rw-rw-
one-var-declaration-per-line.j...	2.86 KB	-rw-rw-rw-
one-var.js	22.37 KB	-rw-rw-rw-
operator-assignment.js	8.58 KB	-rw-rw-rw-
operator-linebreak.js	9.88 KB	-rw-rw-rw-
padded-blocks.js	10.79 KB	-rw-rw-rw-
padding-line-between-statement...	18.85 KB	-rw-rw-rw-
prefer-arrow-callback.js	14.33 KB	-rw-rw-rw-
prefer-const.js	18.27 KB	-rw-rw-rw-
prefer-destructuring.js	10.93 KB	-rw-rw-rw-
prefer-exponentiation-operator...	7.58 KB	-rw-rw-rw-
prefer-named-capture-group.js	5.84 KB	-rw-rw-rw-
prefer-numeric-literals.js	5.7 KB	-rw-rw-rw-
prefer-object-has-own.js	4.24 KB	-rw-rw-rw-
prefer-object-spread.js	10.45 KB	-rw-rw-rw-
prefer-promise-reject-errors.j...	5.37 KB	-rw-rw-rw-
prefer-reflect.js	4.59 KB	-rw-rw-rw-
prefer-regex-literals.js	18.06 KB	-rw-rw-rw-
prefer-rest-params.js	3.39 KB	-rw-rw-rw-
prefer-spread.js	2.78 KB	-rw-rw-rw-
prefer-template.js	11.15 KB	-rw-rw-rw-
quote-props.js	11.82 KB	-rw-rw-rw-
quotes.js	12.41 KB	-rw-rw-rw-
radix.js	6.75 KB	-rw-rw-rw-
require-atomic-updates.js	11.1 KB	-rw-rw-rw-
require-await.js	3.27 KB	-rw-rw-rw-
require-jsdoc.js	3.77 KB	-rw-rw-rw-
require-unicode-regexp.js	5.1 KB	-rw-rw-rw-
require-yield.js	2.05 KB	-rw-rw-rw-
rest-spread-spacing.js	4.03 KB	-rw-rw-rw-
semi-spacing.js	8.71 KB	-rw-rw-rw-
semi-style.js	5.24 KB	-rw-rw-rw-
semi.js	15.87 KB	-rw-rw-rw-
sort-imports.js	10.62 KB	-rw-rw-rw-
sort-keys.js	7.16 KB	-rw-rw-rw-
sort-vars.js	4.04 KB	-rw-rw-rw-
space-before-blocks.js	7.14 KB	-rw-rw-rw-
space-before-function-paren.js	5.87 KB	-rw-rw-rw-
space-in-parens.js	10.55 KB	-rw-rw-rw-
space-infix-ops.js	6.42 KB	-rw-rw-rw-
space-unary-ops.js	12.39 KB	-rw-rw-rw-
spaced-comment.js	12.85 KB	-rw-rw-rw-
strict.js	10.37 KB	-rw-rw-rw-
switch-colon-spacing.js	4.9 KB	-rw-rw-rw-
symbol-description.js	2.04 KB	-rw-rw-rw-
template-curly-spacing.js	4.74 KB	-rw-rw-rw-
template-tag-spacing.js	3.08 KB	-rw-rw-rw-
unicode-bom.js	2.15 KB	-rw-rw-rw-
use-isnan.js	4.64 KB	-rw-rw-rw-
valid-jsdoc.js	20.08 KB	-rw-rw-rw-
valid-typeof.js	4.92 KB	-rw-rw-rw-
vars-on-top.js	5.17 KB	-rw-rw-rw-
wrap-iife.js	7.8 KB	-rw-rw-rw-
wrap-regex.js	1.85 KB	-rw-rw-rw-
yield-star-spacing.js	4.31 KB	-rw-rw-rw-
yoda.js	11.89 KB	-rw-rw-rw-

Code Editor : no-constant-binary-expression.js

/**
 * @fileoverview Rule to flag constant comparisons and logical expressions that always/never short circuit
 * @author Jordan Eldredge <https://jordaneldredge.com>
 */

"use strict";

const globals = require("globals");
const { isNullLiteral, isConstant, isReferenceToGlobalVariable, isLogicalAssignmentOperator } = require("./utils/ast-utils");

const NUMERIC_OR_STRING_BINARY_OPERATORS = new Set(["+", "-", "*", "/", "%", "|", "^", "&", "**", "<<", ">>", ">>>"]);

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/**
 * Checks whether or not a node is `null` or `undefined`. Similar to the one
 * found in ast-utils.js, but this one correctly handles the edge case that
 * `undefined` has been redefined.
 * @param {Scope} scope Scope in which the expression was found.
 * @param {ASTNode} node A node to check.
 * @returns {boolean} Whether or not the node is a `null` or `undefined`.
 * @public
 */
function isNullOrUndefined(scope, node) {
    return (
        isNullLiteral(node) ||
        (node.type === "Identifier" && node.name === "undefined" && isReferenceToGlobalVariable(scope, node)) ||
        (node.type === "UnaryExpression" && node.operator === "void")
    );
}

/**
 * Test if an AST node has a statically knowable constant nullishness. Meaning,
 * it will always resolve to a constant value of either: `null`, `undefined`
 * or not `null` _or_ `undefined`. An expression that can vary between those
 * three states at runtime would return `false`.
 * @param {Scope} scope The scope in which the node was found.
 * @param {ASTNode} node The AST node being tested.
 * @param {boolean} nonNullish if `true` then nullish values are not considered constant.
 * @returns {boolean} Does `node` have constant nullishness?
 */
function hasConstantNullishness(scope, node, nonNullish) {
    if (nonNullish && isNullOrUndefined(scope, node)) {
        return false;
    }

switch (node.type) {
        case "ObjectExpression": // Objects are never nullish
        case "ArrayExpression": // Arrays are never nullish
        case "ArrowFunctionExpression": // Functions never nullish
        case "FunctionExpression": // Functions are never nullish
        case "ClassExpression": // Classes are never nullish
        case "NewExpression": // Objects are never nullish
        case "Literal": // Nullish, or non-nullish, literals never change
        case "TemplateLiteral": // A string is never nullish
        case "UpdateExpression": // Numbers are never nullish
        case "BinaryExpression": // Numbers, strings, or booleans are never nullish
            return true;
        case "CallExpression": {
            if (node.callee.type !== "Identifier") {
                return false;
            }
            const functionName = node.callee.name;

return (functionName === "Boolean" || functionName === "String" || functionName === "Number") &&
                isReferenceToGlobalVariable(scope, node.callee);
        }
        case "LogicalExpression": {
            return node.operator === "??" && hasConstantNullishness(scope, node.right, true);
        }
        case "AssignmentExpression":
            if (node.operator === "=") {
                return hasConstantNullishness(scope, node.right, nonNullish);
            }

/*
             * Handling short-circuiting assignment operators would require
             * walking the scope. We won't attempt that (for now...) /
             */
            if (isLogicalAssignmentOperator(node.operator)) {
                return false;
            }

/*
             * The remaining assignment expressions all result in a numeric or
             * string (non-nullish) value:
             *   "+=", "-=", "*=", "/=", "%=", "<<=", ">>=", ">>>=", "|=", "^=", "&="
             */

return true;
        case "UnaryExpression":

/*
             * "void" Always returns `undefined`
             * "typeof" All types are strings, and thus non-nullish
             * "!" Boolean is never nullish
             * "delete" Returns a boolean, which is never nullish
             * Math operators always return numbers or strings, neither of which
             * are non-nullish "+", "-", "~"
             */

return true;
        case "SequenceExpression": {
            const last = node.expressions[node.expressions.length - 1];

return hasConstantNullishness(scope, last, nonNullish);
        }
        case "Identifier":
            return node.name === "undefined" && isReferenceToGlobalVariable(scope, node);
        case "JSXElement": // ESLint has a policy of not assuming any specific JSX behavior.
        case "JSXFragment":
            return false;
        default:
            return false;
    }
}

/**
 * Test if an AST node is a boolean value that never changes. Specifically we
 * test for:
 * 1. Literal booleans (`true` or `false`)
 * 2. Unary `!` expressions with a constant value
 * 3. Constant booleans created via the `Boolean` global function
 * @param {Scope} scope The scope in which the node was found.
 * @param {ASTNode} node The node to test
 * @returns {boolean} Is `node` guaranteed to be a boolean?
 */
function isStaticBoolean(scope, node) {
    switch (node.type) {
        case "Literal":
            return typeof node.value === "boolean";
        case "CallExpression":
            return node.callee.type === "Identifier" && node.callee.name === "Boolean" &&
              isReferenceToGlobalVariable(scope, node.callee) &&
              (node.arguments.length === 0 || isConstant(scope, node.arguments[0], true));
        case "UnaryExpression":
            return node.operator === "!" && isConstant(scope, node.argument, true);
        default:
            return false;
    }
}

/**
 * Test if an AST node will always give the same result when compared to a
 * boolean value. Note that comparison to boolean values is different than
 * truthiness.
 * https://262.ecma-international.org/5.1/#sec-11.9.3
 *
 * Javascript `==` operator works by converting the boolean to `1` (true) or
 * `+0` (false) and then checks the values `==` equality to that number.
 * @param {Scope} scope The scope in which node was found.
 * @param {ASTNode} node The node to test.
 * @returns {boolean} Will `node` always coerce to the same boolean value?
 */
function hasConstantLooseBooleanComparison(scope, node) {
    switch (node.type) {
        case "ObjectExpression":
        case "ClassExpression":

/**
             * In theory objects like:
             *
             * `{toString: () => a}`
             * `{valueOf: () => a}`
             *
             * Or a classes like:
             *
             * `class { static toString() { return a } }`
             * `class { static valueOf() { return a } }`
             *
             * Are not constant verifiably when `inBooleanPosition` is
             * false, but it's an edge case we've opted not to handle.
             */
            return true;
        case "ArrayExpression": {
            const nonSpreadElements = node.elements.filter(e =>

// Elements can be `null` in sparse arrays: `[,,]`;
                e !== null && e.type !== "SpreadElement");

/*
             * Possible future direction if needed: We could check if the
             * single value would result in variable boolean comparison.
             * For now we will err on the side of caution since `[x]` could
             * evaluate to `[0]` or `[1]`.
             */
            return node.elements.length === 0 || nonSpreadElements.length > 1;
        }
        case "ArrowFunctionExpression":
        case "FunctionExpression":
            return true;
        case "UnaryExpression":
            if (node.operator === "void" || // Always returns `undefined`
                node.operator === "typeof" // All `typeof` strings, when coerced to number, are not 0 or 1.
            ) {
                return true;
            }
            if (node.operator === "!") {
                return isConstant(scope, node.argument, true);
            }

/*
             * We won't try to reason about +, -, ~, or delete
             * In theory, for the mathematical operators, we could look at the
             * argument and try to determine if it coerces to a constant numeric
             * value.
             */
            return false;
        case "NewExpression": // Objects might have custom `.valueOf` or `.toString`.
            return false;
        case "CallExpression": {
            if (node.callee.type === "Identifier" &&
                node.callee.name === "Boolean" &&
                isReferenceToGlobalVariable(scope, node.callee)
            ) {
                return node.arguments.length === 0 || isConstant(scope, node.arguments[0], true);
            }
            return false;
        }
        case "Literal": // True or false, literals never change
            return true;
        case "Identifier":
            return node.name === "undefined" && isReferenceToGlobalVariable(scope, node);
        case "TemplateLiteral":

/*
             * In theory we could try to check if the quasi are sufficient to
             * prove that the expression will always be true, but it would be
             * tricky to get right. For example: `000.${foo}000`
             */
            return node.expressions.length === 0;
        case "AssignmentExpression":
            if (node.operator === "=") {
                return hasConstantLooseBooleanComparison(scope, node.right);
            }

/*
             * Handling short-circuiting assignment operators would require
             * walking the scope. We won't attempt that (for now...)
             *
             * The remaining assignment expressions all result in a numeric or
             * string (non-nullish) values which could be truthy or falsy:
             *   "+=", "-=", "*=", "/=", "%=", "<<=", ">>=", ">>>=", "|=", "^=", "&="
             */
            return false;
        case "SequenceExpression": {
            const last = node.expressions[node.expressions.length - 1];

return hasConstantLooseBooleanComparison(scope, last);
        }
        case "JSXElement": // ESLint has a policy of not assuming any specific JSX behavior.
        case "JSXFragment":
            return false;
        default:
            return false;
    }
}

/**
 * Test if an AST node will always give the same result when _strictly_ compared
 * to a boolean value. This can happen if the expression can never be boolean, or
 * if it is always the same boolean value.
 * @param {Scope} scope The scope in which the node was found.
 * @param {ASTNode} node The node to test
 * @returns {boolean} Will `node` always give the same result when compared to a
 * static boolean value?
 */
function hasConstantStrictBooleanComparison(scope, node) {
    switch (node.type) {
        case "ObjectExpression": // Objects are not booleans
        case "ArrayExpression": // Arrays are not booleans
        case "ArrowFunctionExpression": // Functions are not booleans
        case "FunctionExpression":
        case "ClassExpression": // Classes are not booleans
        case "NewExpression": // Objects are not booleans
        case "TemplateLiteral": // Strings are not booleans
        case "Literal": // True, false, or not boolean, literals never change.
        case "UpdateExpression": // Numbers are not booleans
            return true;
        case "BinaryExpression":
            return NUMERIC_OR_STRING_BINARY_OPERATORS.has(node.operator);
        case "UnaryExpression": {
            if (node.operator === "delete") {
                return false;
            }
            if (node.operator === "!") {
                return isConstant(scope, node.argument, true);
            }

/*
             * The remaining operators return either strings or numbers, neither
             * of which are boolean.
             */
            return true;
        }
        case "SequenceExpression": {
            const last = node.expressions[node.expressions.length - 1];

return hasConstantStrictBooleanComparison(scope, last);
        }
        case "Identifier":
            return node.name === "undefined" && isReferenceToGlobalVariable(scope, node);
        case "AssignmentExpression":
            if (node.operator === "=") {
                return hasConstantStrictBooleanComparison(scope, node.right);
            }

/*
             * Handling short-circuiting assignment operators would require
             * walking the scope. We won't attempt that (for now...)
             */
            if (isLogicalAssignmentOperator(node.operator)) {
                return false;
            }

/*
             * The remaining assignment expressions all result in either a number
             * or a string, neither of which can ever be boolean.
             */
            return true;
        case "CallExpression": {
            if (node.callee.type !== "Identifier") {
                return false;
            }
            const functionName = node.callee.name;

if (
                (functionName === "String" || functionName === "Number") &&
                isReferenceToGlobalVariable(scope, node.callee)
            ) {
                return true;
            }
            if (functionName === "Boolean" && isReferenceToGlobalVariable(scope, node.callee)) {
                return (
                    node.arguments.length === 0 || isConstant(scope, node.arguments[0], true));
            }
            return false;
        }
        case "JSXElement": // ESLint has a policy of not assuming any specific JSX behavior.
        case "JSXFragment":
            return false;
        default:
            return false;
    }
}

/**
 * Test if an AST node will always result in a newly constructed object
 * @param {Scope} scope The scope in which the node was found.
 * @param {ASTNode} node The node to test
 * @returns {boolean} Will `node` always be new?
 */
function isAlwaysNew(scope, node) {
    switch (node.type) {
        case "ObjectExpression":
        case "ArrayExpression":
        case "ArrowFunctionExpression":
        case "FunctionExpression":
        case "ClassExpression":
            return true;
        case "NewExpression": {
            if (node.callee.type !== "Identifier") {
                return false;
            }

/*
             * All the built-in constructors are always new, but
             * user-defined constructors could return a sentinel
             * object.
             *
             * Catching these is especially useful for primitive constructors
             * which return boxed values, a surprising gotcha' in JavaScript.
             */
            return Object.hasOwnProperty.call(globals.builtin, node.callee.name) &&
              isReferenceToGlobalVariable(scope, node.callee);
        }
        case "Literal":

// Regular expressions are objects, and thus always new
            return typeof node.regex === "object";
        case "SequenceExpression": {
            const last = node.expressions[node.expressions.length - 1];

return isAlwaysNew(scope, last);
        }
        case "AssignmentExpression":
            if (node.operator === "=") {
                return isAlwaysNew(scope, node.right);
            }
            return false;
        case "ConditionalExpression":
            return isAlwaysNew(scope, node.consequent) && isAlwaysNew(scope, node.alternate);
        case "JSXElement": // ESLint has a policy of not assuming any specific JSX behavior.
        case "JSXFragment":
            return false;
        default:
            return false;
    }
}

/**
 * Checks if one operand will cause the result to be constant.
 * @param {Scope} scope Scope in which the expression was found.
 * @param {ASTNode} a One side of the expression
 * @param {ASTNode} b The other side of the expression
 * @param {string} operator The binary expression operator
 * @returns {ASTNode | null} The node which will cause the expression to have a constant result.
 */
function findBinaryExpressionConstantOperand(scope, a, b, operator) {
    if (operator === "==" || operator === "!=") {
        if (
            (isNullOrUndefined(scope, a) && hasConstantNullishness(scope, b, false)) ||
            (isStaticBoolean(scope, a) && hasConstantLooseBooleanComparison(scope, b))
        ) {
            return b;
        }
    } else if (operator === "===" || operator === "!==") {
        if (
            (isNullOrUndefined(scope, a) && hasConstantNullishness(scope, b, false)) ||
            (isStaticBoolean(scope, a) && hasConstantStrictBooleanComparison(scope, b))
        ) {
            return b;
        }
    }
    return null;
}

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../shared/types').Rule} */
module.exports = {
    meta: {
        type: "problem",
        docs: {
            description: "Disallow expressions where the operation doesn't affect the value",
            recommended: false,
            url: "https://eslint.org/docs/latest/rules/no-constant-binary-expression"
        },
        schema: [],
        messages: {
            constantBinaryOperand: "Unexpected constant binary expression. Compares constantly with the {{otherSide}}-hand side of the `{{operator}}`.",
            constantShortCircuit: "Unexpected constant {{property}} on the left-hand side of a `{{operator}}` expression.",
            alwaysNew: "Unexpected comparison to newly constructed object. These two values can never be equal.",
            bothAlwaysNew: "Unexpected comparison of two newly constructed objects. These two values can never be equal."
        }
    },

create(context) {
        const sourceCode = context.sourceCode;

return {
            LogicalExpression(node) {
                const { operator, left } = node;
                const scope = sourceCode.getScope(node);

if ((operator === "&&" || operator === "||") && isConstant(scope, left, true)) {
                    context.report({ node: left, messageId: "constantShortCircuit", data: { property: "truthiness", operator } });
                } else if (operator === "??" && hasConstantNullishness(scope, left, false)) {
                    context.report({ node: left, messageId: "constantShortCircuit", data: { property: "nullishness", operator } });
                }
            },
            BinaryExpression(node) {
                const scope = sourceCode.getScope(node);
                const { right, left, operator } = node;
                const rightConstantOperand = findBinaryExpressionConstantOperand(scope, left, right, operator);
                const leftConstantOperand = findBinaryExpressionConstantOperand(scope, right, left, operator);

if (rightConstantOperand) {
                    context.report({ node: rightConstantOperand, messageId: "constantBinaryOperand", data: { operator, otherSide: "left" } });
                } else if (leftConstantOperand) {
                    context.report({ node: leftConstantOperand, messageId: "constantBinaryOperand", data: { operator, otherSide: "right" } });
                } else if (operator === "===" || operator === "!==") {
                    if (isAlwaysNew(scope, left)) {
                        context.report({ node: left, messageId: "alwaysNew" });
                    } else if (isAlwaysNew(scope, right)) {
                        context.report({ node: right, messageId: "alwaysNew" });
                    }
                } else if (operator === "==" || operator === "!=") {

/*
                     * If both sides are "new", then both sides are objects and
                     * therefore they will be compared by reference even with `==`
                     * equality.
                     */
                    if (isAlwaysNew(scope, left) && isAlwaysNew(scope, right)) {
                        context.report({ node: left, messageId: "bothAlwaysNew" });
                    }
                }

}

/*
             * In theory we could handle short-circuiting assignment operators,
             * for some constant values, but that would require walking the
             * scope to find the value of the variable being assigned. This is
             * dependant on https://github.com/eslint/eslint/issues/13776
             *
             * AssignmentExpression() {},
             */
        };
    }
};

${this.title}

Code Editor : no-constant-binary-expression.js