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
Solution 3:
Try an extra =
if (jso === null)
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