typeof(groupId) === 'number' javascript code example

Example 1: type of javascript

//typeof() will return the type of value in its parameters.
//some examples of types: undefined, NaN, number, string, object, array

//example of a practical usage
if (typeof(value) !== "undefined") {//also, make sure that the type name is a string
  	//execute code
}

Example 2: check data type in javascript

typeof("string"); //string
typeof(123); //number