Javascript 默认数组值
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default array values
提问by Derek Adair
Is there a way to assign a default values to arrays in javascript?
有没有办法在javascript中为数组分配默认值？
ex: an array with 24 slots that defaults to 0
前任： an array with 24 slots that defaults to 0
采纳答案by kennebec
Array.prototype.repeat= function(what, L){
while(L) this[--L]= what;
return this;
}
var A= [].repeat(0, 24);
var A= [].repeat(0, 24);
alert(A)
警报（一）
回答by deadrunk
var a = Array.apply(null, Array(24)).map(function() { return 0 });
// or:
var a = Array.apply(null, Array(5)).map(Boolean).map(Number);
回答by Aik
You can use the fillfunction on an array:
您可以fill在数组上使用该函数：
Array(24).fill(0)
Note:fillwas only introduced in ECMAScript 2015 (alias "6"), so as of 2017 browser support is still very limited (for example no Internet Explorer).
注意：fill仅在 ECMAScript 2015 中引入（别名“6”），因此截至 2017 年浏览器支持仍然非常有限（例如没有 Internet Explorer）。
回答by tvanfosson
A little wordy, but it works.
有点罗嗦，但它有效。
var aray = [ 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0 ];
回答by Vito Gentile
If you use a "very modern" browser (check the compatibility table), you can rely on fill:
如果您使用“非常现代”的浏览器（检查兼容性表），您可以依赖fill：
var array = new Array(LENGTH);
array.fill(DEFAULT_VALUE);
For several reasons, the use of new Array()is not appreciated by a lot of developers; so you can do the same as follows:
出于多种原因，new Array()很多开发人员不喜欢使用；所以你可以做同样的事情：
var array = [];
for(var i=0; i<LENGTH; ++i) array.push(DEFAULT_VALUE);
The latter is much more compatible, and as you can see both solutions are represented by two lines of code.
后者更加兼容，正如您所见，这两种解决方案都由两行代码表示。
回答by sajad saderi
the best and fastest solution is :
最好和最快的解决方案是：
Array(length of the array).fill(a default value you want put in the array)
example
例子
Array(5).fill(1)
and result will be
结果将是
[1,1,1,1,1]
you can put any thing you like in it:
你可以放任何你喜欢的东西：
Array(5).fill({name : ""})
Now if you want to change some of the current value in the array you can use
现在，如果您想更改数组中的某些当前值，您可以使用
[the created array ].fill(a new value , start position, end position)
like
喜欢
[1,1,1,1,1].fill("a",1,3)
and output is
和输出是
[1, "a", "a", 1, 1]
回答by Oscar Rieken
If you are using ES6 and up you can use
如果您使用的是 ES6 及更高版本，则可以使用
new Array(24).fill(0);
this also works:
这也有效：
Array.from({ length: 24}, () => 0)
回答by Thomas Eding
I personally use:
我个人使用：
function replicate (n, x) {
var xs = [];
for (var i = 0; i < n; ++i) {
xs.push (x);
}
return xs;
}
Example:
例子：
var hellos = replicate (100, "hello");
回答by kennytm
No.
不。
You have to use a loop.
你必须使用一个循环。
var a = new Array(24);
for (var i = a.length-1; i >= 0; -- i) a[i] = 0;
回答by Tomá?
And now, more cleverly :)
@see JavaScript Array reference
Example on JSFiddle
现在，更聪明的是 :)
@see JavaScript Array reference
Example on JSFiddle
var len = 100;
var ch = '0';
alert ( new Array(len).join( ch ) );
