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disallow reassigning function declarations (no-func-assign)

The "extends": "eslint:recommended" property in a configuration file enables this rule.

JavaScript functions can be written as a FunctionDeclaration function foo() { ... } or as a FunctionExpression var foo = function() { ... };. While a JavaScript interpreter might tolerate it, overwriting/reassigning a function written as a FunctionDeclaration is often indicative of a mistake or issue.

function foo() {}
foo = bar;

Rule Details

This rule disallows reassigning function declarations.

Examples of incorrect code for this rule:

/*eslint no-func-assign: "error"*/

function foo() {}
foo = bar;

function foo() {
    foo = bar;
}

var a = function hello() {
  hello = 123;
};

Examples of incorrect code for this rule, unlike the corresponding rule in JSHint:

/*eslint no-func-assign: "error"*/

foo = bar;
function foo() {}

Examples of correct code for this rule:

/*eslint no-func-assign: "error"*/

var foo = function () {}
foo = bar;

function foo(foo) { // `foo` is shadowed.
    foo = bar;
}

function foo() {
    var foo = bar;  // `foo` is shadowed.
}

Version

This rule was introduced in ESLint 0.0.9.

Resources

© JS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/rules/no-func-assign