JavaScript for/in Statement
❮ JavaScript Statements Reference
Example
Loop through the properties of an object:
var person = {fname:"John", lname:"Doe", age:25};
var text = "";
var x;
for (x in person) {
text += person[x] + " ";
}
Try it Yourself »
Definition and Usage
The for/in statement loops through the properties of an object.
The block of code inside the loop will be executed once for each property.
JavaScript supports different kinds of loops:
- for - loops through a block of code a number of times
- for/in - loops through the properties of an object
- while - loops through a block of code while a specified condition is true
- do/while - loops through a block of code once, and then repeats the loop while a specified condition is true
Note: Do not use the for/in statement to loop through arrays where index order is important. Use the for statement instead.
Browser Support
| Statement | |||||
|---|---|---|---|---|---|
| for/in | Yes | Yes | Yes | Yes | Yes |
Syntax
for (var in
object) {
code block to be executed
}
Parameter Values
| Parameter | Description |
|---|---|
| var | Required. A variable that iterates over the properties of an object |
| object | Required. The specified object that will be iterated |
Technical Details
| JavaScript Version: | ECMAScript 1 |
|---|
Related Pages
JavaScript Tutorial: JavaScript For Loop
JavaScript Reference: JavaScript for Statement
❮ JavaScript Statements Reference
