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Invoke a function for each own enumerable property of an object.
npm install @stdlib/utils-for-own
var forOwn = require( '@stdlib/utils-for-own' );
Invokes a function
for each own enumerable property of an object
.
function log( value, key ) {
console.log( '%s: %d', key, value );
}
var obj = {
'a': 1,
'b': 2,
'c': 3,
'd': 4
};
forOwn( obj, log );
/* e.g., =>
a: 1
b: 2
c: 3
d: 4
*/
The invoked function
is provided three arguments:
-
value
: object property value -
key
: object property -
obj
: the input object
To terminate iteration before visiting all properties, the provided function must explicitly return false
.
function log( value, key ) {
console.log( '%s: %d', key, value );
return false;
}
var obj = {
'a': 1,
'b': 2,
'c': 3,
'd': 4
};
forOwn( obj, log );
// e.g., => a: 1
To set the function execution context, provide a thisArg
.
function sum( value ) {
this.sum += value;
this.count += 1;
}
var obj = {
'a': 1,
'b': 2,
'c': 3,
'd': 4
};
var context = {
'sum': 0,
'count': 0
};
forOwn( obj, sum, context );
var mean = context.sum / context.count;
// returns 2.5
- The function returns the input
object
. - The function determines the list of own enumerable properties before invoking the provided function. Hence, any modifications made to the input
object
after calling this function (such as adding and removing properties) will not affect the list of visited properties. - Property iteration order is not guaranteed.
var fromCodePoint = require( '@stdlib/string-from-code-point' );
var forOwn = require( '@stdlib/utils-for-own' );
function update( value, key, obj ) {
console.log( '%s: %d', key, value );
obj[ key ] *= value;
}
var obj;
var key;
var i;
obj = {};
for ( i = 0; i < 26; i++ ) {
key = fromCodePoint( 97 + i );
obj[ key ] = i;
}
forOwn( obj, update );
console.log( obj );
-
@stdlib/utils-for-each
: invoke a function for each element in a collection. -
@stdlib/utils-for-in
: invoke a function for each own and inherited enumerable property of an object.
This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
Copyright © 2016-2024. The Stdlib Authors.