handling null in json or javascript

Question

Im using an ajax json response to build some html to place in a webpage. Occasionally I'll come across an empty value in my json. This results in an empty object being placed into the html.

I would prefer not to check that each value is not an object, as that doesn't seem efficient. Is there a better way? my code works like this

var firstVar=jsonObj.fristVar;
var secVar=jsonObj.secVar;
var thirdVar=jsonObj.thirdVar;
var fourthVar=jsonObj.fourthVar;
...
var htmlResponse='<div class="'+firstVar+'">'+secVar+'<span class="'+thirdVar+'">'+fourthVar+'</span>...';
jQuery("body").html(htmlResponse);

Community · Accepted Answer · 2017-05-23 10:25:18Z

2

If you want to specify default values when they are null, you can just do this:

var firstVar = jsonObj.firstVar || '';
var secVar = jsonObj.secVar || 'No Value';
...

Unrelated to your question, have you looked at an implementation of jQuery templating?

edited May 23, 2017 at 10:25

CommunityBot

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answered Dec 9, 2009 at 23:51

Chetan S

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3 Comments

Christian C. Salvadó Over a year ago

That will set the default value not only when the members are null, also when they are 0, false, undefined, empty string and NaN.

pedalpete Over a year ago

The code you've written above makes sense, and it should work, but I'm still getting the response of "[object object]" when using var firstVar=jsonObj.firstVar || ''; - When I alert(firstVar.toSource), I get ({}). Any idea why I'm still getting this?

pedalpete Over a year ago

also, I wasn't familiar with jQuery templating before, and I'm not really sure why it is beneficial, but I'll dig into it deeper. Thanks for expanding my knowledge.

Kaleb Brasee · Accepted Answer · 2009-12-09 23:59:16Z

1

You could use a tertiary operator:

var firstVar = (jsonObj.fristVar != null) ? jsonObj.fristVar : "some default value";

answered Dec 9, 2009 at 23:59

Kaleb Brasee

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