angular.isDefined()
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.1/angular.min.js"></script>
<h1>angular.isDefined()</h1>
JavaScript
var foo;
var checkFoo = function(value){
return "CheckFoo : " + (value && value !== "");
}
console.log(angular.isString(foo)); // false
console.log(checkFoo(foo));
foo = null;
console.log(angular.isString(foo)); // true
console.log(checkFoo(foo));
foo = "";
console.log(angular.isString(foo)); // true
console.log(checkFoo(foo));
foo = "foo";
console.log(angular.isString(foo)); // true
console.log(checkFoo(foo));
foo = {};
console.log(angular.isString(foo)); // true
console.log(checkFoo(foo));
foo = {key: 'value'};
console.log(angular.isString(foo)); // true
console.log(checkFoo(foo));