正如@oportocala所提到的，空字符串不会产生预期的空数组。

因此，要反击，请执行以下操作：

str
.split(',')
.map(entry => entry.trim())
.filter(entry => entry)

对于预期整数数组，请执行以下操作：

str
.split(',')
.map(entry => parseInt(entry))
.filter(entry => typeof entry ==='number')

请注意：

var a = "";
var x = new Array();
x = a.split(",");
alert(x.length);

将提醒1

对于逗号分隔字符串的字符串数组：

let months = ["January","Feb"];
let monthsString = months.join(", ");

将逗号分隔的字符串传递到此函数，它将返回一个数组，如果找不到逗号分隔字符串，则返回null。

function splitTheString(CommaSepStr) {
    var ResultArray = null;

    // Check if the string is null or so.
    if (CommaSepStr!= null) {

        var SplitChars = ',';

        // Check if the string has comma of not will go to else
        if (CommaSepStr.indexOf(SplitChars) >= 0) {
            ResultArray = CommaSepStr.split(SplitChars);

        }
        else {

            // The string has only one value, and we can also check
            // the length of the string or time and cross-check too.
            ResultArray = [CommaSepStr];
        }
    }
    return ResultArray;
}

let str = "January,February,March,April,May,June,July,August,September,October,November,December"

let arr = str.split(',');

这将导致：

["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]

如果要将以下内容转换为：

["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]

这：

"January,February,March,April,May,June,July,August,September,October,November,December";

use:

str = arr.join(',')

var array = string.split(',');

MDN引用，对于极限参数的可能意外行为非常有用。（提示：“a，b，c”.split（“，”，2）指向[“a”，“b”]，而不是[“a，”b，c“]。）