如何使用jQuery判断所选结果是否为空?

$("#experiences tr")

For the above one,how to judge if it's empty or not?

对于上面这个，如何判断它是否为空?

I thought its boolean value should be false,but seems not.

我认为它的布尔值应该是假的，但似乎不是。

5 个解决方案

#1

use the length property:

使用长度属性:

$("#experiences tr").length

if it's 0 it's empty

如果它是0，它就是空的

#2

var experienceRows = $('#experiences tr'),
    len = experienceRows.length;

if ( len ) {
} else {
}

#3

Or, if you just want to affect only the empty elements, use

或者，如果您只想影响空元素，请使用

$('#experiences tr:empty')

or the other way around:

或者反过来说:

$('#experiences tr:not(:empty)')

#4

$("#experiences tr:empty")

#5

//More Improved and Accurate - Trim white spaces as well

//Define

function trim(str) {
    return( ("" + str).replace(/^\s+/,'').replace(/[\s]+/g,' ').replace(/\s+$/,'') ); 
}

//Call

if(trim(frmObj.element.value).length ==0) { //true }

#1