How to append something to an array?

如何在JavaScript中将一个对象（如字符串或数字）附加到数组中？

---

使用push()函数附加到数组：

// initialize array
var arr = [
    "Hi",
    "Hello",
    "Bonjour"
];

// append new value to the array
arr.push("Hola");

console.log(arr);

---

If you're only appending a single variable, then push() works just fine. If you need to append another array, use concat() :

var ar1 = [1, 2, 3];
var ar2 = [4, 5, 6];

var ar3 = ar1.concat(ar2);

alert(ar1);
alert(ar2);
alert(ar3);

Will spit out:

"1,2,3"
"4,5,6"
"1,2,3,4,5,6"

The concat does not affect ar1 and ar2 unless reassigned, for example:

ar1 = ar1.concat(ar2);
alert(ar1);

Will display:

"1,2,3,4,5,6"

Lots of great info here

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Some quick benchmarking (each test = 500k appended elements and the results are averages of multiple runs) showed the following:

Firefox 3.6 (Mac):

Small arrays: arr[arr.length] = b is faster (300ms vs. 800ms)

Large arrays: arr.push(b) is faster (500ms vs. 900ms)

Safari 5.0 (Mac):

Small arrays: arr[arr.length] = b is faster (90ms vs. 115ms)

Large arrays: arr[arr.length] = b is faster (160ms vs. 185ms)

Google Chrome 6.0 (Mac):

Small arrays: No significant difference (and Chrome is FAST! Only ~38ms !!)

Large arrays: No significant difference (160ms)

I like the arr.push() syntax better, but I think I'd be better off with the arr[arr.length] Version, at least in raw speed. I'd love to see the results of an IE run though.

---

My benchmarking loops:

function arrpush_small() {
    var arr1 = [];
    for (a = 0; a < 100; a++)
    {
        arr1 = [];
        for (i = 0; i < 5000; i++)
        {
            arr1.push('elem' + i);
        }
    }
}

function arrlen_small() {
    var arr2 = [];
    for (b = 0; b < 100; b++)
    {
        arr2 = [];
        for (j = 0; j < 5000; j++)
        {
            arr2[arr2.length] = 'elem' + j;
        }
    }
}


function arrpush_large() {
    var arr1 = [];
    for (i = 0; i < 500000; i++)
    {
        arr1.push('elem' + i);
    }
}

function arrlen_large() {
    var arr2 = [];
    for (j = 0; j < 500000; j++)
    {
        arr2[arr2.length] = 'elem' + j;
    }
}

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