grep()?jQuery.grep(array, function[, invert]) (alias $.grep) keeps items that pass a boolean test (since jQuery 1.0). Optional invert flips the test — keep where the callback returns false.
$.grep(array, function(element, index) {
return true; // keep this element
})
$.grep([0, 1, 2], function (n) { return n > 0; })
// → [1, 2]
$.grep([0, 1, 2], function (n) { return n > 0; }, true)
// → [0] (invert)| Need | Use |
|---|---|
| Keep items that pass a test | $.grep(arr, fn) |
| Keep items that fail a test | $.grep(arr, fn, true) |
| Transform values | $.map(arr, fn) |
| Native array filter | arr.filter(fn) |
grep()Pass an array-like list, a boolean callback, and optionally invert.
length).(element, index) and returns true or false.$.grep(array, fn) to keep passing items.true as the third argument to keep failing items instead.| Piece | Required? | Role |
|---|---|---|
array | Yes | Array-like object to search |
function | Yes | Boolean test: (element, index) → Boolean |
invert | No | If true, keep where callback is false |
| Return | — | New Array (source unchanged) |
function grep(array, fn, invert):
result = []
for i from 0 to array.length - 1:
pass = fn(array[i], i) // must be boolean-ish
if invert:
keep = not pass
else:
keep = pass
if keep:
result.push(array[i])
return result // new array; original untouchedKeep these facts handy while filtering with jQuery.
| Topic | Detail |
|---|---|
| Syntax | jQuery.grep(array, function[, invert]) |
| Since | jQuery 1.0 |
| Callback | (element, index) → Boolean |
this | Global window (not the element) |
| Mutates? | No — returns a new array |
| Invert | true → keep failed tests |
| vs map | $.map transforms; $.grep selects |
Filter [0, 1, 2, 5, 9] with a few common $.grep rules.
Short, copy-ready snippets. Open DevTools Console, or use Try It Yourself for a live editor.
Official simple filter: drop zeros and negatives.
var result = $.grep([0, 1, 2], function (n) {
return n > 0;
});
console.log(result); // [1, 2][0, 1, 2].true only when n > 0.1 and 2 pass; 0 fails.[1, 2] — the original list is unchanged.Same callback, opposite keep rule with invert: true.
var result = $.grep([0, 1, 2], function (n) {
return n > 0;
}, true);
console.log(result); // [0]n > 0.true means keep where the callback is false.0 fails n > 0.[0] — handy when the reject rule is easier to write.Use both callback arguments, like the official demo.
var arr = [1, 9, 3, 8, 6, 1, 5, 9, 4, 7];
var result = $.grep(arr, function (n, i) {
return n !== 5 && i > 4;
});
console.log(result); // [1, 9, 4, 7]n is the value; i is its index.i > 4 drops the first five slots.n !== 5 drops the 5 at index 6.1, 9, 4, 7.grepFilter again to remove every 9.
var arr = [1, 9, 4, 7, 3, 8, 6, 9, 1];
arr = $.grep(arr, function (a) {
return a !== 9;
});
console.log(arr); // [1, 4, 7, 3, 8, 6, 1]9s.a !== 9.arr = $.grep(...) replaces your variable with the filtered list.Check these before filtering real data.
Unlike $.map, returning a number or string does not transform the item — it is only tested for truthiness. Use true/false on purpose.
$.grep needs array-like input. For object maps, use Object.values(obj) first, or iterate with $.each.
this is windowInside the callback, this is the global object — not the current element. Use the first argument for the value.
Array.filter in modern JSOn true arrays, arr.filter(fn) is native and clear. Keep $.grep when you need invert or array-like input in a jQuery codebase.
jQuery.grep() is a data utility available since jQuery 1.0+ in all browsers that load jQuery. It does not depend on a special DOM API — only on jQuery being present.
Works wherever jQuery runs in the browser. For modern pure-array code without jQuery, Array.prototype.filter is the native alternative.
Bottom line: Use $.grep(arr, fn) in jQuery apps. Use arr.filter(fn) when you only need native array filtering.
| Approach | Cost | Best for |
|---|---|---|
$.grep(arr, fn) | O(n) | Filter once over n items |
| Chained greps | O(n + m + …) | Clear multi-step rules |
arr.filter(fn) | O(n) | Native arrays without invert |
One pass is enough for a single rule. Chain greps only when each step is easier to read — combine into one callback if the list is huge and you need every micro-optimization.
$.grep(arr, fn) → new filtered array.true/false (not a new value).true keeps failed tests.One line: use $.grep to select items with a boolean test — flip with invert, and use $.map when you need to change values.
Merge objects and defaults with jQuery’s extend utility.
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