How To Check If A Javascript Object Contains Null Value Or It Itself Is Null

Say I'm accessing a JavaScript Object called jso in Java and I'm using the following statement to test if it's null if (jso == null) However, this statement seems to return true w

Solution 1:

To determine whether the target reference contains a member with a null value, you'll have to write your own function as none exist out of the box to do this for you. One simple approach would be:

functionhasNull(target) {
    for (var member in target) {
        if (target[member] == null)
            returntrue;
    }
    returnfalse;
}

Needless to say, this only goes one level deep, so if one of the members on target contains another object with a null value, this will still return false. As an exmaple of usage:

var o = { a: 'a', b: false, c: null };
document.write('Contains null: ' + hasNull(o));

Will print out:

Contains null: true

In contrast, the following will print out false:

var o = { a: 'a', b: false, c: {} };
document.write('Contains null: ' + hasNull(o));

Solution 2:

This is just for your reference. Do not upvote.

var jso;
document.writeln(typeof(jso)); // 'undefined'document.writeln(jso); // value of jso = 'undefined'

jso = null;
document.writeln(typeof(jso)); // null is an 'object'document.writeln(jso); // value of jso = 'null'document.writeln(jso == null); // truedocument.writeln(jso === null); // truedocument.writeln(jso == "null"); // false

http://jsfiddle.net/3JZfT/3/

Solution 3:

Try an extra =

if (jso === null)