检查对象数组？ [英] Check if object is array?

问题描述

我想写一个不接受字符串列表，或者一个字符串的函数。如果它是一个字符串，那么我想它只是一个项目转换为数组。那么我可以遍历它，不用担心出错。

I'm trying to write a function that either accepts a list of strings, or a single string. If it's a string, then I want to convert it to an array with just the one item. Then I can loop over it without fear of an error.

那么，如何检查是否变量是一个数组？

So how do I check if the variable is an array?

我围捕以下各种解决方案，并创建了一个 jsperf测试。

I've rounded up the various solutions below and created a jsperf test.

推荐答案

要找到类对象在ECMAScript标准给出的方法是使用的toString 方法从的Object.prototype 。

The method given in the ECMAScript standard to find the class of Object is to use the toString method from Object.prototype.

if( Object.prototype.toString.call( someVar ) === '[object Array]' ) {
    alert( 'Array!' );
}

或者你可以使用的typeof 来测试，如果它是一个字符串：

Or you could use typeof to test if it is a String:

if( typeof someVar === 'string' ) {
    someVar = [ someVar ];
}

或者，如果你不关心性能，你可以只是做一个 CONCAT 到一个新的空Array。

Or if you're not concerned about performance, you could just do a concat to a new empty Array.

someVar = [].concat( someVar );

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编辑：查看了彻底治疗从<一个 HREF =htt​​p://stackoverflow.com/users/157247/tj-crowder> @TJ克罗德的博客，如张贴在低于他的评论。

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Check out a thorough treatment from @T.J. Crowder's blog, as posted in his comment below.

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