typescript string empty or null 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

Example 4: typescript if string is null or empty

function empty(e) {
  switch (e) {
    case "":
    case 0:
    case "0":
    case null:
    case false:
    case typeof(e) == "undefined":
      return true;
    default:
      return false;
  }
}

empty(null) // true
empty(0) // true
empty(7) // false
empty("") // true
empty((function() {
    return ""
})) // false