338d7ee8a7
* change es6 challenges rest operator to param * fix rest parameter typos * change rest operator to parameter in guide * fix casing * change rest operator to rest parameter in guide * change rest operator to rest parameter in curriculum * remove extra whitespace * remove whitespaces * remove whitespace * fix: removed arabic file * fix: removed chinese file
1.1 KiB
1.1 KiB
title
| title |
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| Function Length |
Function Length
The length property on the function object holds the number of arguments expected by the function when called.
function noArgs() { }
function oneArg(a) { }
console.log(noArgs.length); // 0
console.log(oneArg.length); // 1
ES2015 Syntax
ES2015, or ES6 as it is commonly called, introduced the rest parameter and default function parameters. Both of these additions change the way the length property works.
If either the rest parameter or default parameters are used in a function declaration the length property will only include the number of arguments before a rest parameter or a default parameter.
function withRest(...args) { }
function withArgsAndRest(a, b, ...args) { }
function withDefaults(a, b = 'I am the default') { }
console.log(withRest.length); // 0
console.log(withArgsAndRest.length); // 2
console.log(withDefaults.length); // 1
More Information on Function.length can be found on Mozilla's MDN Docs.