Check if Object Array and ignore all else [duplicate]

Question

I have a multiple divs returning an array like this:

[{"k":"Model","v":"box"},{"k":"Color","v":"blue"},{"k":"Size","v":"med"},{"k":"Type","v":"good"}]

Sometimes, non-array items come back and I want to ignore those.
Could be blank spaces or random un-ordered blank lists. So I only want to process only the arrays that come back leave the rest blank.
How could I check if it is array and ignore the rest?

jQuery('.overview').each(function () {
   var $overview = jQuery(this),
       specs = jQuery.parseJSON($overview.html());
   if ( !! specs) {
       $overview.html('<div class="bullet_spec"></div>');
       jQuery.each(specs, function () {
           $overview.children('div').append('<ul class="specs"><li class="label">' + this.k + ' : ' + this.v + '</li></ul>');
       });
   } else { // leave blank?? not sure what to do here
   }
});

Here is my fiddle: http://jsfiddle.net/veGPN/
Thanks

if( !! specs )? That's a double negative, why not just if(specs)? — Preston S
– Preston S, Commented Jan 23, 2014 at 20:53

p.s.w.g · Accepted Answer · 2014-01-23 22:15:47Z

5

You can use the isArray function from jQuery:

if (jQuery.isArray(specs)) {
   $overview.html('<div class="bullet_spec"></div>');
   jQuery.each(specs, function () {
       $overview.children('div').append('<ul class="specs"><li class="label">' + this.k + ' : ' + this.v + '</li></ul>');
   });
}

However, it appears the problem in your fiddle is that some of the elements (x) aren't even Json. So it's not that the result isn't an array, it's that it is unable to parse the result at all. You can simply wrap your parsing script with a try/catch to handle this gracefully:

var $overview = jQuery(this), spec;
try {
    specs = jQuery.parseJSON($overview.html());
} catch(e) {
    return;
}

Demonstartion

edited Jan 23, 2014 at 22:15

answered Jan 23, 2014 at 20:52

p.s.w.g

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4 Comments

SteveAustin Over a year ago

Thanks, none of these suggestions work in my fiddle so I think I might have deeper problems.

p.s.w.g Over a year ago

@SteveAustin The problem in your fiddle is that x isn't valid Json. See my updated answer.

SteveAustin Over a year ago

Thanks, That works. I was weary to use try / catch after looking in to it more. I ended up simply testing for [ and if not there leave empty.

var a = jQuery(this).text(),            str = a.substr(0, 1),        if (str.indexOf('[') == -1) {            jQuery(this).empty();        }

This seems to work for my purposes.

p.s.w.g Over a year ago

@SteveAustin That still wouldn't guarantee that the string was valid Json (e.g. [+] would pass). A try/catch is still safer, but yeah, maybe that's sufficient for your particular use case.

Goran.it · Accepted Answer · 2014-01-23 21:00:07Z

0

This is common and crossbrowser code to check error-free for an array :

if (Object.prototype.toString.call( someVar ) === '[object Array]' ) {

answered Jan 23, 2014 at 21:00

Goran.it

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