You can use .is() . ... Or you could just test the length property to see if one was found. ... Keep in mind that empty means no white space either. ... <看更多>

$('input#edit-keys-1').blur(function(){. tmpval = $(this).val();. if(tmpval == '') {. $(this).addClass('empty');. $(this).removeClass('not-empty');. } ... ... <看更多>

To check if the <div> element contains the secondary class, you use the following code: const div = document.querySelector('.info'); div. ... <看更多>

Selects all elements of type A. Type refers to the type of tag, so div , p and ul are all different element types. Examples. div selects all div elements. p ... ... <看更多>