Use a JSON array with objects with javascript

Question

Hi,

I have a function that will get a JSON array with objects. In the function I will be able to loop through the array, access a property and use that property. Like this:

Variable that I will pass to the function will look like this:

[{"id":28,"Title":"Sweden"}, {"id":56,"Title":"USA"}, {"id":89,"Title":"England"}]

function test(myJSON)
{
    // maybe parse my the JSON variable?
    // and then I want to loop through it and access my IDs and my titles
}

Any suggestions how I can solve it?

Regards, Fredrik

Answer 1

By 'JSON array containing objects' I guess you mean a string containing JSON?

If so you can use the safe var myArray = JSON.parse(myJSON) method (either native or included using JSON2), or the usafe var myArray = eval("(" + myJSON + ")"). eval should normally be avoided, but if you are certain that the content is safe, then there is no problem.

After that you just iterate over the array as normal.

for (var i = 0; i < myArray.length; i++) {
    alert(myArray[i].Title);
}

Answer 2

Your question feels a little incomplete, but I think what you're looking for is a way of making your JSON accessible to your code:

if you have the JSON string as above then you'd just need to do this

var jsonObj = eval('[{"id":28,"Title":"Sweden"}, {"id":56,"Title":"USA"}, {"id":89,"Title":"England"}]');

then you can access these vars with something like jsonObj[0].id etc

Let me know if that's not what you were getting at and I'll try to help.

M

Answer 3

This isn't a single JSON object. You have an array of JSON objects. You need to loop over array first and then access each object. Maybe the following kickoff example is helpful:

var arrayOfObjects = [{"id":28,"Title":"Sweden"}, {"id":56,"Title":"USA"}, {"id":89,"Title":"England"}];

for (var i = 0; i < arrayOfObjects.length; i++) {
    var object = arrayOfObjects[i];
    for (var property in object) {
        alert('item ' + i + ': ' + property + '=' + object[property]);
    }
    // If property names are known beforehand, you can also just do e.g.
    // alert(object.id + ',' + object.Title);
}

To learn more about JSON, check this article.

Update: if the array of JSON objects is actually passed in as a plain vanilla string, then you would indeed need eval() here.

var string = '[{"id":28,"Title":"Sweden"}, {"id":56,"Title":"USA"}, {"id":89,"Title":"England"}]';
var arrayOfObjects = eval(string);
// ...