JavaScript for/inStatement

Examples

Loop through object properties:

var person = {fname:"John", lname:"Doe", age:25}; var text = ""; var x; for (x in person) { text += person[x] + " "; }

textOutput:

John Doe 25

The for/in statement loops through the properties of an object.

Each time the code in the loop executes, it performs an operation on an array element or an object property.

JavaScript supports different types of loops:

for - loop a block of code a certain number of times
for/in - loop through the properties of an object
while - loop a specified block of code when a specified condition is true
do/while- also loop a specified block of code when a specified condition is true

Note:Do not use the for/in statement to loop through array indices. You can use theforstatement instead.

Statement
for/in	Yes	Yes	Yes	Yes	Yes

for (var in object) {
The block of code to be executed
}

Parameter	Description
var	Required. The specified variable can be an array element or an object property.
object	Required. Specifies the object to iterate over.

JavaScript Version:	1.0

JavaScript Tutorial:JavaScript For Loop