compare undefined in javascript code example
Example 1: javascript if undefined
if(typeof comment === 'undefined') {
alert('Variable "comment" is undefined.');
} else if(comment === null){
alert('Variable "comment" is null.');
}
Example 2: how to check if object is undefined in javascript
if (typeof something === "undefined") {
alert("something is undefined");
}
Example 3: assign this value or if it is undefined this other value javascript
var x;
var y;
var z = 12;
x = !(y === undefined) ? y : z;
console.log(x);