The some()
method tests whether at least one element in the array passes the test implemented by the provided function. It returns a Boolean value.
arr.some(callback(element[, index[, array]])[, thisArg])
callback
A function to test for each element, taking three arguments:
element
index
Optional
array
Optional
some()
was called upon.thisArg
Optional
this
when executing callback
.true
if the callback function returns a truthy value for at least one element in the array. Otherwise, false
.
The some()
method executes the callback
function once for each element present in the array until it finds the one where callback
returns a truthy value (a value that becomes true when converted to a Boolean). If such an element is found, some()
immediately returns true
. Otherwise, some()
returns false
. callback
is invoked only for indexes of the array with assigned values. It is not invoked for indexes which have been deleted or which have never been assigned values.
callback
is invoked with three arguments: the value of the element, the index of the element, and the Array object being traversed.
If a thisArg
parameter is provided to some()
, it will be used as the callback's this
value. Otherwise, the value undefined
will be used as its this
value. The this
value ultimately observable by callback
is determined according to the usual rules for determining the this
seen by a function.
some()
does not mutate the array on which it is called.
The range of elements processed by some()
is set before the first invocation of callback
. Elements appended to the array after the call to some()
begins will not be visited by callback
. If an existing, unvisited element of the array is changed by callback
, its value passed to the visiting callback
will be the value at the time that some()
visits that element's index. Elements that are deleted are not visited.
Caution: Calling this method on an empty array returns false
for any condition!
some()
was added to the ECMA-262 standard in the 5th edition, and it may not be present in all implementations of the standard. You can work around this by inserting the following code at the beginning of your scripts, allowing use of some()
in implementations which do not natively support it.
This algorithm is exactly the one specified in ECMA-262, 5th edition, assuming Object
and TypeError
have their original values and that fun.call
evaluates to the original value of Function.prototype.call()
.
// Production steps of ECMA-262, Edition 5, 15.4.4.17 // Reference: http://es5.github.io/#x15.4.4.17 if (!Array.prototype.some) { Array.prototype.some = function(fun, thisArg) { 'use strict'; if (this == null) { throw new TypeError('Array.prototype.some called on null or undefined'); } if (typeof fun !== 'function') { throw new TypeError(); } var t = Object(this); var len = t.length >>> 0; for (var i = 0; i < len; i++) { if (i in t && fun.call(thisArg, t[i], i, t)) { return true; } } return false; }; }
The following example tests whether any element in the array is bigger than 10.
function isBiggerThan10(element, index, array) { return element > 10; } [2, 5, 8, 1, 4].some(isBiggerThan10); // false [12, 5, 8, 1, 4].some(isBiggerThan10); // true
Arrow functions provide a shorter syntax for the same test.
[2, 5, 8, 1, 4].some(x => x > 10); // false [12, 5, 8, 1, 4].some(x => x > 10); // true
To mimic the function of the includes()
method, this custom function returns true
if the element exists in the array:
const fruits = ['apple', 'banana', 'mango', 'guava']; function checkAvailability(arr, val) { return arr.some(function(arrVal) { return val === arrVal; }); } checkAvailability(fruits, 'kela'); // false checkAvailability(fruits, 'banana'); // true
const fruits = ['apple', 'banana', 'mango', 'guava']; function checkAvailability(arr, val) { return arr.some(arrVal => val === arrVal); } checkAvailability(fruits, 'kela'); // false checkAvailability(fruits, 'banana'); // true
const TRUTHY_VALUES = [true, 'true', 1]; function getBoolean(value) { 'use strict'; if (typeof value === 'string') { value = value.toLowerCase().trim(); } return TRUTHY_VALUES.some(function(t) { return t === value; }); } getBoolean(false); // false getBoolean('false'); // false getBoolean(1); // true getBoolean('true'); // true
Desktop | ||||||
---|---|---|---|---|---|---|
some |
1 | 12 | 1.5 | 9 | 9.5 | 3 |
Mobile | ||||||
---|---|---|---|---|---|---|
some |
≤37 | 18 | 4 | 10.1 | 1 | 1.0 |
Server | |
---|---|
some |
0.1.100 |
Array.prototype.every()
Array.prototype.forEach()
Array.prototype.find()
TypedArray.prototype.some()
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some