for each...in

The for each...in statement iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed.

Syntax

for each (variable in object) {
  statement
}

variable

Variable to iterate over property values, optionally declared with the var keyword. This variable is local to the function, not to the loop.

object

Object for which the properties are iterated.

statement

A statement to execute for each property. To execute multiple statements within the loop, use a block statement ({ ... }) to group those statements.

Description

Some built-in properties are not iterated over. These include all built-in methods of objects, e.g. String's indexOf method. However, all user-defined properties are iterated over.

Examples

Using for each...in

Warning: Never use a loop like this on arrays. Only use it on objects. See for...in for more details.

The following snippet iterates over an object's properties, calculating their sum:

var sum = 0;
var obj = {prop1: 5, prop2: 13, prop3: 8};

for each (var item in obj) {
  sum += item;
}

console.log(sum); // logs "26", which is 5+13+8

Specifications

Not part of a current ECMA-262 specification. Implemented in JavaScript 1.6 and deprecated.

Браузерная совместимость

Firefox specific note

• for each...in удалён только из Nightly Firefox 53

Смотрите также

• for...in - аналогичный оператор по перебору имён свойств.
• for...of - аналогичный оператор, перебирающий значения свойств, но может быть использован только для перебираемых (iteratable) типов, so not for generic objects
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