If one of two elements exists, do something

问题

I currently do this to check if one of two elements exists:

if ($(".element1").length > 0 || $(".element2").length > 0) {
  //do stuff...
}

Is there a better way to rewrite the same? I mean, is .length the same as .length > 0?

回答1:

if ($(".element1").is('*') || $(".element2").is('*')) {
    // code
}

EDIT (per comment) Select elements by multiple classes in one call:

if ($(".element1, .element2").is('*')) {
    // code
}

回答2:

if ( $('#myDiv')[0] ) { //do something }

..works best!

Found here.

回答3:

All jQuery elements have the .length property. You can just go:

if ($('img').length) // Implies: If this element exists..

http://jqueryfordesigners.com/element-exists/

回答4:

!$.isEmptyObject($.find('#urId'))

this will return "true" if the element exists and False if not

cheers :)

回答5:

Just use .each().

$(".element1").each(function(){
  //Do Something here
}

Simple...

回答6:

See Extremely updated version of this plugin here! Now uses callback function so you can maintain chainability if you choose. Can completely replace if statement or can still be used within if statement

You could create a very simple jQuery plug-in for this, as such:

jsFiddle

(function($) {
    if (!$.exist) {
        $.extend({
            exist: function(elm) {
                if (typeof elm == null) return false;
                if (typeof elm != "object") elm = $(elm);
                return elm.length ? true : false;
            }
        });
        $.fn.extend({
            exist: function() {
                return $.exist($(this));
            }
        });
    }
})(jQuery);

USE

//  With ID 
$.exist("#eleID");
//  OR
$("#eleID").exist();

//  With class name
$.exist(".class-name");
//  OR
$(".class-name").exist();

//  With just tag // prolly not best idea aS there will be other tags on site
$.exist("div");
//  OR
$("div").exist();

With your If statement

if ($(".element1").exist() || $(".element2").exist()) {
    ...stuff...
}

Of course this plugin could be further extended to be much more fancy (handling multiple calls at once, creating non-existing elements based on a pram), but as it stand now, it does a very simple, very needed function ... Does this element exist? return True or False

jsFiddle

回答7:

$.fn.exists = function(ifExists) {
    return this.length ? ifExists.call(this, this) : this;
};

usage:

$('.element1, .element2').exists(function(els) {
    // this and els refers to $('.element1, .element2')
});

来源：https://stackoverflow.com/questions/1899103/if-one-of-two-elements-exists-do-something

标签

jquery

exists