eslint/docs/rules/prefer-rest-params.md

   1 # Suggest using the rest parameters instead of `arguments` (prefer-rest-params)
   2
   3 There are rest parameters in ES2015.
   4 We can use that feature for variadic functions instead of the `arguments` variable.
   5
   6 `arguments` does not have methods of `Array.prototype`, so it's a bit of an inconvenience.
   7
   8 ## Rule Details
   9
  10 This rule is aimed to flag usage of `arguments` variables.
  11
  12 ## Examples
  13
  14 Examples of **incorrect** code for this rule:
  15
  16 ```js
  17 /*eslint prefer-rest-params: "error"*/
  18
  19 function foo() {
  20     console.log(arguments);
  21 }
  22
  23 function foo(action) {
  24     var args = Array.prototype.slice.call(arguments, 1);
  25     action.apply(null, args);
  26 }
  27
  28 function foo(action) {
  29     var args = [].slice.call(arguments, 1);
  30     action.apply(null, args);
  31 }
  32 ```
  33
  34 Examples of **correct** code for this rule:
  35
  36 ```js
  37 /*eslint prefer-rest-params: "error"*/
  38
  39 function foo(...args) {
  40     console.log(args);
  41 }
  42
  43 function foo(action, ...args) {
  44     action.apply(null, args); // or `action(...args)`, related to the `prefer-spread` rule.
  45 }
  46
  47 // Note: the implicit arguments can be overwritten.
  48 function foo(arguments) {
  49     console.log(arguments); // This is the first argument.
  50 }
  51 function foo() {
  52     var arguments = 0;
  53     console.log(arguments); // This is a local variable.
  54 }
  55 ```
  56
  57 ## When Not To Use It
  58
  59 This rule should not be used in ES3/5 environments.
  60
  61 In ES2015 (ES6) or later, if you don't want to be notified about `arguments` variables, then it's safe to disable this rule.
  62
  63 ## Related Rules
  64
  65 * [prefer-spread](prefer-spread.md)