how to check if its a sting js code example

Example 1: if string javascript

if (typeof myVar === 'string') { /* code */ };

Example 2: if variable is string javascript

var booleanValue = true; 
var numericalValue = 354;
var stringValue = "This is a String";
var stringObject = new String( "This is a String Object" );
alert(typeof booleanValue) // displays "boolean"
alert(typeof numericalValue) // displays "number"
alert(typeof stringValue) // displays "string"
alert(typeof stringObject) // displays "object"