Object manipulation statements | for-in

The for-in loop allows you to cycle through the properties of an object to display or manipulate their values.

for (var variable_name in object_name) {
JavaScript statements go here

For example, if you want to cycle through the properties of an instance of MyCustomizedComputer object in order to display the values on the screen then using for-in loop is a time saver since you don’t have to type each property name.

//This is the object
function MyCustomizedComputer (CPU, RAM, SSD) {
	this.CPU = CPU;
	this.RAM = RAM;
	this.SSD = SSD;

//This is the new instance
var DanComputer = new MyCustomizedComputer ("i5", "8GB", "120GB");

//This is for-in loop
for (var DisplayProperties in DanComputer) {
	document.write (DanComputer [DisplayProperties] );

Notice DanComputer[DisplayProperties] which is unfamiliar. It is an array to store the values of the properties.

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