if variable is string javascript

if (typeof myVar === 'string'){
    //I am indeed a string
}

if (typeof myVar === 'integer'){
    //I am indeed an integer
}

if (typeof myVar === 'boolean'){
    //I am indeed a boolean
}

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"