具有条件的Array.join() [英] Array.join() with condition

问题描述

如何在条件下使用Array.join()函数

例如:

var name = ['','aa','','','bb'];
var s = name.join(', ');

输出为:', aa, , ,'bb',

我想添加一个条件，该条件将仅显示不为空的单词:"aa, bb"

I want to add a condition that will display only words that are not empty: "aa, bb"

推荐答案

您可以使用

You can use Array#filter to remove empty elements from array and then use Array#join on filtered array.

arr.filter(Boolean).join(', ');

在这里，filter的回调函数是布尔构造函数.与

Here, the callback function to filter is Boolean constructor. This is same as

// ES5 equivalent
arr.filter(function(el) {
    return Boolean(el);
}).join(', ');

由于空字符串在JavaScript中是虚假的，因此Boolean('')将返回false，并且该元素将从数组中跳过.胶水将过滤后的非空字符串数组连接起来.

As empty strings are falsy in JavaScript, Boolean('') will return false and the element will be skipped from the array. And the filtered array of non-empty strings is joined by the glue.

var arr = ['', 'aa', '', '', 'bb'];
var s = arr.filter(Boolean).join(', ');

console.log(s);

您还可以使用 String#trim 从字符串中删除前导和尾随空格.

You can also use String#trim to remove leading and trailing spaces from the string.

arr.filter(x => x.trim()).join(', ');

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