js Array vs [],以及是否为空的判断

时间:2021-01-11 20:42:24

两者基本相同,唯一不同点在于初始化:

var a = [],            // these are the same
b = new Array(), // a and b are arrays with length 0 c = ['foo', 'bar'], // these are the same
d = new Array('foo', 'bar'), // c and d are arrays with 2 strings // these are different:
e = [3] // e.length == 1, e[0] == 3
f = new Array(3), // f.length == 3, f[0] == undefined

也就是说Array(arg),其中的arg是指生成数组的长度。

参考:What’s the difference between “Array()” and “[]” while declaring a JavaScript array?

检查array是否为空:

if (array === undefined || array.length == 0) {
// array empty or does not exist
}