Usage of with in JS

The WITH statement makes it easy to reference an existing property of an object, but it cannot be used to add a property to an object, and you must explicitly reference the object if you want to create a new property for it.

Sometimes in a piece of code to use a property or method of an object more than once, you can use the WITH statement to reduce the code:

Usage: With (< OBJECT >) < statement >

Example 1:

function person () {

This.name= "Green";

This.age= "20";

}

var p = new person ();

With (p) {

var str = "name" +name+ "<br>";

str = "Age" +age;

document.write (str);

}

Example 2:

The With statement is typically used to shorten the amount of code that must be written in a particular case. In the following example, note the repeated use of Math:

x = Math.Cos (3 * Math.PI) + Math.sin (MATH.LN10);

y = Math.tan (MATH.E);

When you use the WITH statement, the code becomes shorter and easier to read:

With (Math) {

x = cos (3 * PI) + sin (LN10);

y = tan (E);

}