no-func-assign

Disallow reassigning function declarations

JavaScript functions can be written as a FunctionDeclaration function foo() { ... } or as a FunctionExpression const 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;
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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 baz() {
    baz = bar;
}

let a = function hello() {
  hello = 123;
};
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Examples of incorrect code for this rule, unlike the corresponding rule in JSHint:

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

foo = bar;
function foo() {}
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Examples of correct code for this rule:

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

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

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

function qux() {
    const qux = bar;  // `qux` is shadowed.
}
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Handled by TypeScript

It is safe to disable this rule when using TypeScript because TypeScript's compiler enforces this check.

Version

This rule was introduced in ESLint v0.0.9.

Resources

• Rule source
• Tests source