TypedArray.prototype.some()

The some() method tests whether some element in the typed array passes the test implemented by the provided function. This method has the same algorithm as Array.prototype.some(). TypedArray is one of the typed array types here.

Syntax

// Arrow function
some((element) => { ... } )
some((element, index) => { ... } )
some((element, index, array) => { ... } )

// Callback function
some(callbackFn)
some(callbackFn, thisArg)

// Inline callback function
some(function callbackFn(element) { ... })
some(function callbackFn(element, index) { ... })
some(function callbackFn(element, index, array){ ... })
some(function callbackFn(element, index, array) { ... }, thisArg)

Parameters

callbackFn

Function to test for each element, taking three arguments:

element

The current element being processed in the typed array.

index

The index of the current element being processed in the typed array.

array

The typed array some was called upon.

thisArg

Optional. Value to use as this when executing callback.

Return value

true if the callback function returns a truthy value for any array element; otherwise, false.

Description

The some method executes the callbackFn function once for each element present in the typed array until it finds one where callbackFn returns a true value. If such an element is found, some immediately returns true. Otherwise, some returns false.

callbackFn 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 passed to callbackFn when invoked, for use as its this value. Otherwise, the value undefined will be passed for use as its this value.  The this value ultimately observable by callbackFn is determined according to the usual rules for determining the this seen by a function.

some does not mutate the typed array on which it is called.

Polyfill

Since there is no global object with the name TypedArray, polyfilling must be done on an "as needed" basis.

// https://tc39.github.io/ecma262/#sec-%typedarray%.prototype.some
if (!Uint8Array.prototype.some) {
  Object.defineProperty(Uint8Array.prototype, 'some', {
    value: Array.prototype.some
  });
}

If you need to support truly obsolete JavaScript engines that don't support Object.defineProperty, it's best not to polyfill Array.prototype methods at all, as you can't make them non-enumerable.

Examples

Testing size of all typed array elements

The following example tests whether any element in the typed array is bigger than 10.

function isBiggerThan10(element, index, array) {
  return element > 10;
}
new Uint8Array([2, 5, 8, 1, 4]).some(isBiggerThan10); // false
new Uint8Array([12, 5, 8, 1, 4]).some(isBiggerThan10); // true

Testing typed array elements using arrow functions

Arrow functions provide a shorter syntax for the same test.

new Uint8Array([2, 5, 8, 1, 4]).some(elem => elem > 10); // false
new Uint8Array([12, 5, 8, 1, 4]).some(elem => elem > 10); // true

Specifications

Specification
ECMAScript Language Specification (ECMAScript)
# sec-%typedarray%.prototype.some

Browser compatibility

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See also