检查所有数组项是否都未定义或为空字符串

Question

How to check if all of items are undefined or empty string '' ?

var items = [variable_1, variable_2, variable_3];

Is there any nice way to do that instead of big if ? Not ES6.

Answer 1

You can use every :

The every() method tests whether all elements in the array pass the test implemented by the provided function. It returns a Boolean value.

Answer 2

一个使用Array.prototype.some来查找至少一个不是undefined或''的元素的内衬，如果找到一个，则返回true

!items.some(item => item != undefined || item != '')

Answer 3

Here's another one I just thought of:

if (array.join("") === "") 
  // all undefined or ""

Note that that'll also be true if an element is null , not undefined , so it may or may not suit the OP. Advantage is that it doesn't need a callback function.