jQuery Utilities & Helpers
These helpers work with arrays/objects, merge data, inspect types, and coordinate async tasks. They don’t touch the DOM but are useful in most jQuery projects.
Quick Reference
| Method | Description | Example |
|---|---|---|
$.each(arr|obj, fn) | Iterate arrays/objects (side effects). | $.each([1,2], (i,v)=>...) |
$.map(arr|obj, fn) | Transform items to a new array. | $.map([1,2], v=>v*2) |
$.grep(arr, fn) | Filter array by predicate. | $.grep([1,2,3], v=>v%2) |
$.inArray(val, arr) | Index of value (or -1). | $.inArray('b',['a','b']) |
$.extend([deep], target, ...src) | Shallow/deep copy merge of objects. | $.extend(true, {}, a, b) |
$.merge(first, second) | Merge arrays into first. | $.merge([], a); $.merge(dest, b) |
$.type(val) | Normalized JS type string. | $.type(new Date()) === 'date' |
$.param(obj) | Serialize object to query string. | $.param({a:1, t:['x','y']}) |
$.isPlainObject(obj) | True if created via {} or new Object. | $.isPlainObject({a:1}) |
$.uniqueSort(arrayLike) | Remove duplicates & sort DOM elements. | $.uniqueSort($('.x,.y,.x').get()) |
$.when(p1, p2, ...) | Wait for multiple deferreds. | $.when(a,b).done(...) |
$.noop | No-operation function placeholder. | .fail($.noop) |
Note: Legacy helpers like
$.trim, $.isFunction, and $.isArray are deprecated—prefer native String.prototype.trim, typeof v === 'function', and Array.isArray.1) $.each() & $.map()
$.each([1,2,3], function(i, v){ ... });
$.map({ a:1, b:2 }, function(v, k){ return k+':'+v; });
10) $.when() & $.noop
$.when($.get('/a'), $.get('/b')).done(function(){ ... }).fail($.noop);
Tip: Use
$.extend(true, {}, ...) to create deep copies without mutating your source objects.