typescript check string null or empty code example

Example 1: javascript if string empty

// Test whether strValue is empty or is None
if (strValue) {
    //do something
}
// Test wheter strValue is empty, but not None 
if (strValue === "") {
    //do something
}

Example 2: how to check is null or empty in typescript

if(typeof propertyValue!='undefined' && propertyValue){
	//execute code here
}

Example 3: empty string in javascript

var s; // undefined
var s = ""; // ""
s.length // 0