javascript clarification for handling null values

Question

Ok i have little section of javascript syntax and i am very confuse how null behaves. There is a lot of discussion about null values but i cant seem to figure out the problem! Please help me. Here is the script.

var jsonData = '<?php echo $jsonData;?>';


    if (jsonData)
    {           
        console.log('jsonData is '+ jsonData);// null or not this section is always executed! why?
    }else{
        ini(jsonData);
    }

I tried using '===', '!' operators but still not working as expected

<?php ?> tags are wrapped in quote..returned value will always be string like 'null' which is truthy value.. — Rayon
– Rayon, Commented Mar 1, 2016 at 5:04
I see so its a string lol. Well console.log didn't show any quotation though. — n4mi
– n4mi, Commented Mar 1, 2016 at 5:07
Console will never show quotes..console.log('hi'); => hi not "hi".. — Rayon
– Rayon, Commented Mar 1, 2016 at 5:08

Community · Accepted Answer · 2017-05-23 12:31:05Z

1

this line var jsonData = '<?php echo $jsonData;?>'; will always be a string, and if the value returned from php is null, then you will end up having var jsonData = 'null';

try this code

if (jsonData && jsonData != 'null' )
{           
    console.log('jsonData is '+ jsonData); //now this code will be executed only if jsonData is not null
}
else
{
    ini(jsonData);
}

or as mentioned by Rayon above, replace the assignment statement with

var jsonData = <?php echo $jsonData;?>;

edited May 23, 2017 at 12:31

CommunityBot

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answered Mar 1, 2016 at 5:04

gurvinder372

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Comments

Sagar · Accepted Answer · 2016-03-01 05:26:44Z

0

Make a check for "Null" value as well as "NAN" in your condition.

answered Mar 1, 2016 at 5:26

Sagar

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