在此页

• 句法
• 描述
• Polyfill
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

fill() method changes all elements in an array to a static value, from a start index (default 0 ) to an end index (default array.length ). It returns the modified array.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

句法

arr.fill(value[, start[, end]])
					

参数

value

Value to fill the array with. (Note all elements in the array will be this exact value.)

start 可选

Start index, default 0 .

end 可选

End index, default arr.length .

返回值

The modified array, filled with value .

描述

• 若 start is negative, it is treated as array.length + start .
• 若 end is negative, it is treated as array.length + end .
• fill is intentionally generic: it does not require that its this value be an Array 对象。
• fill is a mutator method: it will change the array itself and return it, not a copy of it.
• If the first parameter is an object, each slot in the array will reference that object.

Polyfill

if (!Array.prototype.fill) {
  Object.defineProperty(Array.prototype, 'fill', {
    value: function(value) {
      // Steps 1-2.
      if (this == null) {
        throw new TypeError('this is null or not defined');
      }
      var O = Object(this);
      // Steps 3-5.
      var len = O.length >>> 0;
      // Steps 6-7.
      var start = arguments[1];
      var relativeStart = start >> 0;
      // Step 8.
      var k = relativeStart < 0 ?
        Math.max(len + relativeStart, 0) :
        Math.min(relativeStart, len);
      // Steps 9-10.
      var end = arguments[2];
      var relativeEnd = end === undefined ?
        len : end >> 0;
      // Step 11.
      var finalValue = relativeEnd < 0 ?
        Math.max(len + relativeEnd, 0) :
        Math.min(relativeEnd, len);
      // Step 12.
      while (k < finalValue) {
        O[k] = value;
        k++;
      }
      // Step 13.
      return O;
    }
  });
}
					

If you need to support truly obsolete JavaScript engines that don't support Object.defineProperty , it's best not to polyfill Array.prototype methods at all, as you can't make them non-enumerable.

范例

Using fill

[1, 2, 3].fill(4)                // [4, 4, 4]
[1, 2, 3].fill(4, 1)             // [1, 4, 4]
[1, 2, 3].fill(4, 1, 2)          // [1, 4, 3]
[1, 2, 3].fill(4, 1, 1)          // [1, 2, 3]
[1, 2, 3].fill(4, 3, 3)          // [1, 2, 3]
[1, 2, 3].fill(4, -3, -2)        // [4, 2, 3]
[1, 2, 3].fill(4, NaN, NaN)      // [1, 2, 3]
[1, 2, 3].fill(4, 3, 5)          // [1, 2, 3]
Array(3).fill(4)                 // [4, 4, 4]
[].fill.call({ length: 3 }, 4)   // {0: 4, 1: 4, 2: 4, length: 3}
// A single object, referenced by each slot of the array:
let arr = Array(3).fill({}) // [{}, {}, {}]
arr[0].hi = "hi"            // [{ hi: "hi" }, { hi: "hi" }, { hi: "hi" }]
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Array.prototype.fill' in that specification.

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
fill	Chrome 45	Edge 12	Firefox 31	IE No	Opera 32	Safari 8	WebView Android 45	Chrome Android 45	Firefox Android 31	Opera Android 32	Safari iOS 8	Samsung Internet Android 5.0	nodejs 4.0.0 4.0.0 0.12 Disabled Disabled From version 0.12: this feature is behind the --harmony runtime flag.

图例

完整支持

完整支持

不支持

不支持

用户必须明确启用此特征。

用户必须明确启用此特征。

另请参阅

• Array
• TypedArray.prototype.fill()

元数据

• 最后修改： May 20, 2020

相关话题

1. 标准内置对象
2. Array
3. 特性
   1. Array.prototype.length
   2. Array.prototype[@@unscopables]
4. 方法
   1. Array.from()
   2. Array.isArray()
   3. Array.of()
   4. Array.prototype.concat()
   5. Array.prototype.copyWithin()
   6. Array.prototype.entries()
   7. Array.prototype.every()
   8. Array.prototype.fill()
   9. Array.prototype.filter()
   10. Array.prototype.find()
   11. Array.prototype.findIndex()
   12. Array.prototype.flat()
   13. Array.prototype.flatMap()
   14. Array.prototype.forEach()
   15. Array.prototype.includes()
   16. Array.prototype.indexOf()
   17. Array.prototype.join()
   18. Array.prototype.keys()
   19. Array.prototype.lastIndexOf()
   20. Array.prototype.map()
   21. Array.prototype.pop()
   22. Array.prototype.push()
   23. Array.prototype.reduce()
   24. Array.prototype.reduceRight()
   25. Array.prototype.reverse()
   26. Array.prototype.shift()
   27. Array.prototype.slice()
   28. Array.prototype.some()
   29. Array.prototype.sort()
   30. Array.prototype.splice()
   31. Array.prototype.toLocaleString()
   32. Array.prototype.toSource()
   33. Array.prototype.toString()
   34. Array.prototype.unshift()
   35. Array.prototype.values()
   36. Array.prototype[@@iterator]()
   37. get Array[@@species]
5. 继承：
6. Function
7. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
8. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
9. Object
10. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
11. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()