Injа vascript, a variable declaration is

? Optional

? Mandatory

? Not allowed

? None of the given

Optional

Explanation:

Variable declaration means when you declaring a variable in the code, whenever you want to use a variable you should declare it or define the variable with come constant.

Example

var name;

The variable has no value after the statement (technically it has undefined value). Declaring a variable without var keyword is not recommended. An current global variable may accidentally be overwritten.

Example

a=2;

The range of variables declared without var keywords becomes global regardless of where they are declared