This plugin plugin can still be used as simple as if ($(ele).exist()) { /* DO WORK */ } or using a callback.

jsFiddle

;;(function($) {
 if (!$.exist) {
 $.extend({
 exist: function() {
 var ele, cbmExist, cbmNotExist;
 if (arguments.length) {
 for (x in arguments) {
 switch (typeof arguments[x]) {
 case 'function':
 if (typeof cbmExist == "undefined") cbmExist = arguments[x];
 else cbmNotExist = arguments[x];
 break;
 case 'object':
 if (arguments[x] instanceof jQuery) ele = arguments[x];
 else {
 var obj = arguments[x];
 for (y in obj) {
 if (typeof obj[y] == 'function') {
 if (typeof cbmExist == "undefined") cbmExist = obj[y];
 else cbmNotExist = obj[y];
 }
 if (typeof obj[y] == 'object' && obj[y] instanceof jQuery) ele = obj[y];
 if (typeof obj[y] == 'string') ele = $(obj[y]);
 }
 }
 break;
 case 'string':
 ele = $(arguments[x]);
 break;
 }
 }
 }
 
 if (typeof cbmExist == 'function') {
 var exist = ele.length > 0 ? true : false;
 if (exist) {
 return ele.each(function(i) { cbmExist.apply(this, [exist, ele, i]); });
 }
 else if (typeof cbmNotExist == 'function') {
 cbmNotExist.apply(ele, [exist, ele]);
 return ele;
 }
 else {
 if (ele.length <= 1) return ele.length > 0 ? true : false;
 else return ele.length;
 }
 }
 else {
 if (ele.length <= 1) return ele.length > 0 ? true : false;
 else return ele.length;
 }
 
 return false;
 }
 });
 $.fn.extend({
 exist: function() {
 var args = [$(this)];
 if (arguments.length) for (x in arguments) args.push(arguments[x]);
 return $.exist.apply(,ドル args);
 }
 });
 }
})(jQuery);

You can use an if: statement, or you can create your own callback.

Keep in mind, the callback has 2 possible creations.

The second function will fire if the element does NOT exist. However, if you choose to set only one function, then it will only fire when the element exist. Thus the "chain" will die if the selected element does "not" exist. Of course, if it does exist, the first function will fire and chainability will continue.

On another note, keep in mind, using a callback method helps to maintain chainability. This means the element is returned and you can continue chaining commands as with any other jQuery method!

jsFiddle

if ($.exist('#eleID')) { /* DO WORK */ } // param as STRING
if ($.exist($('#eleID'))) { /* DO WORK */ } // param as jQuery OBJECT
if ($('#eleID').exist()) { /* DO WORK */ } // enduced on jQuery OBJECT
$.exist('#eleID', function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
}, function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element DOES NOT EXIST */
})
$('#eleID').exist(function() { // enduced on jQuery OBJECT with CALLBACK METHOD
 /* DO WORK */
 /* Will ONLY FIRE IF EXIST */
})
$.exist({ // param is OBJECT containing 2 key|value pairs: element = STRING, callback = METHOD
 element: '#eleID',
 callback: function() {
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
 }
})

This plugin can be used in an if statement like if ($(ele).exist()) { /* DO WORK */ } or using a callback.

;;(function($) {
 if (!$.exist) {
 $.extend({
 exist: function() {
 var ele, cbmExist, cbmNotExist;
 if (arguments.length) {
 for (x in arguments) {
 switch (typeof arguments[x]) {
 case 'function':
 if (typeof cbmExist == "undefined") cbmExist = arguments[x];
 else cbmNotExist = arguments[x];
 break;
 case 'object':
 if (arguments[x] instanceof jQuery) ele = arguments[x];
 else {
 var obj = arguments[x];
 for (y in obj) {
 if (typeof obj[y] == 'function') {
 if (typeof cbmExist == "undefined") cbmExist = obj[y];
 else cbmNotExist = obj[y];
 }
 if (typeof obj[y] == 'object' && obj[y] instanceof jQuery) ele = obj[y];
 if (typeof obj[y] == 'string') ele = $(obj[y]);
 }
 }
 break;
 case 'string':
 ele = $(arguments[x]);
 break;
 }
 }
 }
 
 if (typeof cbmExist == 'function') {
 var exist = ele.length > 0 ? true : false;
 if (exist) {
 return ele.each(function(i) { cbmExist.apply(this, [exist, ele, i]); });
 }
 else if (typeof cbmNotExist == 'function') {
 cbmNotExist.apply(ele, [exist, ele]);
 return ele;
 }
 else {
 if (ele.length <= 1) return ele.length > 0 ? true : false;
 else return ele.length;
 }
 }
 else {
 if (ele.length <= 1) return ele.length > 0 ? true : false;
 else return ele.length;
 }
 
 return false;
 }
 });
 $.fn.extend({
 exist: function() {
 var args = [$(this)];
 if (arguments.length) for (x in arguments) args.push(arguments[x]);
 return $.exist.apply(,ドル args);
 }
 });
 }
})(jQuery);

You may specify one or two callbacks. The first one will fire if the element exists, the second one will fire if the element does not exist. However, if you choose to pass only one function, it will only fire when the element exists. Thus, the chain will die if the selected element does not exist. Of course, if it does exist, the first function will fire and the chain will continue.

Keep in mind that using the callback variant helps maintain chainability – the element is returned and you can continue chaining commands as with any other jQuery method!

if ($.exist('#eleID')) { /* DO WORK */ } // param as STRING
if ($.exist($('#eleID'))) { /* DO WORK */ } // param as jQuery OBJECT
if ($('#eleID').exist()) { /* DO WORK */ } // enduced on jQuery OBJECT
$.exist('#eleID', function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
}, function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element DOES NOT EXIST */
})
$('#eleID').exist(function() { // enduced on jQuery OBJECT with CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
})
$.exist({ // param is OBJECT containing 2 key|value pairs: element = STRING, callback = METHOD
 element: '#eleID',
 callback: function() {
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
 }
})

Extreme Update_{Oct 2, '13}

Originally I made this plugin to provide a bit more acute sense than simply if ($(ele).length) { /* DO WORK */ }. Sure that is simple and easy, but I didn't like how it took me "outside" of typical "jQuery style". I really wanted a $.fn.exist() method in order to maintain readable markup. Also, the simple plugins so often previously suggested, do not account for developer error. Thus the creation of the very simple plugin found here (minified ).

I soon decided to kick it up a notch and provide for more functionality in checking against developer mistakes as well as provide a bit more functionality. The thought lead me to the update on _{Jun 6, '13} found over here (minified ). Now I've finally put together a version I really like!

This new version of the plugin can still be used as simple as if ($(ele).exist()) { /* DO WORK */ }, however I found that to be a bit "against the grain" with jQuery typical markup style. I thought, "Why the if statement? Shouldn't that be in a callback?" Now it is! Behold, the new, bigger, stronger, callbackier $.exist() Plugin!

jsFiddle

The use is extremely easy. You can still use in an if: statement, or you can create your own callback. Keep in mind, the callback has 2 possible creations.(削除) You can create the call back with NO PARAMETERS such as function() {} and it will ONLY FIRE IF the element EXIST. However, if you provide a parameter, such as function(exist) {} or even function(bob) {}, then the callback will ALWAYS FIRE even if the element does NOT EXIST. In the second scenario, your parameter, no mater what you name it, becomes a BOOLEAN of wether or not the element exist. (削除ここまで)

UPDATE: After a little more personal use, I found the "parameter" setup to be a bit flawed. I've since replaced it with a better working ideal of allowing for a "second" function. The second function will fire if the element does NOT exist. However, if you choose to set only one function, then it will only fire when the element exist. Thus the "chain" will die if the selected element does "not" exist. Of course, if it does exist, the first function will fire and chainability will continue.

Minified jsFiddle

;;(function($){$.exist||($.extend({exist:function(){var a,c,d;if(arguments.length)for(x in arguments)switch(typeof arguments[x]){case "function":"undefined"==typeof c?c=arguments[x]:d=arguments[x];break;case "object":if(arguments[x]instanceof jQuery)a=arguments[x];else{var b=arguments[x];for(y in b)"function"==typeof b[y]&&("undefined"==typeof c?c=b[y]:d=b[y]),"object"==typeof b[y]&&b[y]instanceof jQuery&&(a=b[y]),"string"==typeof b[y]&&(a=$(b[y]))}break;case "string":a=$(arguments[x])}if("function"==typeof c){var e=0<a.length?!0:!1;if(e)return a.each(function(b){c.apply(this,[e,a,b])});if("function"==typeof d)return d.apply(a,[e,a]),a}return 1>=a.length?0<a.length?!0:!1:a.length}}),$.fn.extend({exist:function(){var a=[$(this)];if(arguments.length)for(x in arguments)a.push(arguments[x]);return $.exist.apply(,ドルa)}}))})(jQuery);

NOTE: All minified versions were made using Google Closure

This plugin plugin can still be used as simple as if ($(ele).exist()) { /* DO WORK */ } or using a callback.

jsFiddle

You can use an if: statement, or you can create your own callback.

Keep in mind, the callback has 2 possible creations.

The second function will fire if the element does NOT exist. However, if you choose to set only one function, then it will only fire when the element exist. Thus the "chain" will die if the selected element does "not" exist. Of course, if it does exist, the first function will fire and chainability will continue.

if ($.exist('#eleID')) { /* DO WORK */ } // param as STRING
if ($.exist($('#eleID'))) { /* DO WORK */ } // param as jQuery OBJECT
if ($('#eleID').exist()) { /* DO WORK */ } // enduced on jQuery OBJECT
$.exist('#eleID', function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
})
$('#eleID').exist(function() { // enduced on jQuery OBJECT with CALLBACK METHOD
 /* DO WORK */
 /* Will ONLY FIRE IF EXIST */
})
$.exist({  // param is OBJECT containing 2 key|value pairs: element = STRING, callback = METHOD
 element: '#eleID',
 callback: function(exist) {
 /* DO WORK */
 /* Will ALWAYS FIRE */
 }
})
$.exist({ // param is OBJECT containing 2 key|value pairs: element = jQuery OBJECT, callback = METHOD
 element: $('#eleID'),
 callback: function() {
 /* DO WORK */
 /* Will ONLY FIRE IF EXIST */
 }
})
$.exist([ // param is ARRAY containing 2 key|value pairs: jQuery STRING, METHOD
 '#eleID',
 function(exist) {
 /* DO WORK */
  /* Will ONLY FIRE IF EXIST */
 }
])
// Will only callback if true'
$.exist([ // param is ARRAY containing 2 key|value pairs: jQuery OBJECT, METHOD
 $('#eleID'),
 function() {
  /* DO WORK */
 /* Will ONLY FIRE IF EXIST */
 }
])

$.exist({ element: '#eleID' }); // param is OBJECT containing 1 key|value pairs: element = STRING
$.exist({ element: $('#eleID') }); // param is OBJECT containing 1 key|value pairs: element = jQuery OBJECT

if ($.exist('#eleID')) { /* DO WORK */ } // param as STRING
if ($.exist($('#eleID'))) { /* DO WORK */ } // param as jQuery OBJECT
if ($('#eleID').exist()) { /* DO WORK */ } // enduced on jQuery OBJECT
$.exist('#eleID', function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
}, function() { // param is STRING && CALLBACK METHOD
 /* DO WORK */
 /* This will ONLY fire if the element DOES NOT EXIST */
})
$('#eleID').exist(function() { // enduced on jQuery OBJECT with CALLBACK METHOD
 /* DO WORK */
 /* Will ONLY FIRE IF EXIST */
})
$.exist({ // param is OBJECT containing 2 key|value pairs: element = STRING, callback = METHOD
 element: '#eleID',
 callback: function() {
 /* DO WORK */
 /* This will ONLY fire if the element EXIST */
 }
})