The forEach()
method executes a provided function once for each value in the Set
object, in insertion order.
The forEach()
method executes a provided function once for each value in the Set
object, in insertion order.
// Arrow function forEach(() => { /* ... */ } ) forEach((value) => { /* ... */ } ) forEach((value, key) => { /* ... */ } ) forEach((value, key, set) => { /* ... */ } ) // Callback function forEach(callbackFn) forEach(callbackFn, thisArg) // Inline callback function forEach(function() { /* ... */ }) forEach(function(value) { /* ... */ }) forEach(function(value, key) { /* ... */ }) forEach(function(value, key, set) { /* ... */ }) forEach(function(value, key, set) { /* ... */ }, thisArg)
callback
Function to execute for each element, taking three arguments:
value
, key
The current element being processed in the Set
. As there are no keys in Set
, the value is passed for both arguments.
set
The Set
object which forEach()
was called upon.
thisArg
Value to use as this
when executing callbackFn
.
The forEach()
method executes the provided callback
once for each value which actually exists in the Set
object. It is not invoked for values which have been deleted. However, it is executed for values which are present but have the value undefined
.
callback
is invoked with three arguments:
Set
There are no keys in Set
objects, however, so the first two arguments are both values contained in the Set
. This is to make it consistent with other forEach()
methods for Map
and Array
.
If a thisArg
parameter is provided to forEach()
, it will be passed to callback
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 callback
is determined according to the usual rules for determining the this
seen by a function.
Each value is visited once, except in the case when it was deleted and re-added before forEach()
has finished. callback
is not invoked for values deleted before being visited. New values added before forEach()
has finished will be visited.
forEach()
executes the callback
function once for each element in the Set
object; it does not return a value.
The following code logs a line for each element in a Set
object:
function logSetElements(value1, value2, set) { console.log(`s[${value}] = ${value2}`); } new Set(['foo', 'bar', undefined]).forEach(logSetElements); // logs: // "s[foo] = foo" // "s[bar] = bar" // "s[undefined] = undefined"
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forEach |
38 |
12 |
25 |
11 |
25 |
8 |
38 |
38 |
25 |
25 |
8 |
3.0 |
1.0 |
0.12.0 |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/forEach