CODEWITHSUNDEEP
jqueryajax
MajAfy
MajAfy

Reputation: 3097

don't work data.length when data returned from ajax

I trying to get some data in json type with ajax in jQuery, so I wrote this code :

$.ajax({
    url: link.attr('href'),
    type: 'post',
    data: 'post=true',
    dataType: 'json',
    success: function(data){
        if (data.length > 0) {
            ldLayer.fadeOut('slow');
        }else{
            alert('no data');
        }
    }
});

But when the data is null the if will true and ldLayer.fadeOut('slow'); will run !

UPDATE: The console.log(data) result is : [null]

Upvotes: 4

Views: 18425

Answers (2)

Suresh Atta
Suresh Atta

Reputation: 121998

Simply Check like this 

if (data)   {
    ldLayer.fadeOut('slow');
} else {
    alert('no data');
}

Upvotes: 2

apsillers
apsillers

Reputation: 115950

You're getting back an array of results. In the problem case you describe, you're getting back an array with a single null element. An empty array ([]) has a length of 0, but an array with a single null element ([null]) has length 1.

In the client, you can check if any of the array's elements are non-null:

success: function(data){
    var foundSomething = false;

    for(var i=0; i<data.length; ++i) {
        if(data[i] !== null) foundSomething = true;
        break;
    }

    if(foundSomething) {
        ldLayer.fadeOut('slow');
    }else{
        alert('no data');
    }
}

However, a much better approach would be to fix your server-side code so it doesn't send back arrays with null elements. If you don't have control over the server code, however, the client-side solution I've provided above is your best bet.

Upvotes: 4

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