Why can't I access object properties in javascript?

Question

I've a simply loop in node.js:

exports.sample = function (req, res) {
    var images = req.query.images;
    images.forEach(function (img) {
        console.log(img);
        console.log(img.path, img.id);
        console.log(img);
    });
    res.end();
};

The result is:

{"id":42,"path":"gGGfNIMGFK95mxQ66SfAHtYm.jpg"}
undefined undefined
{"id":42,"path":"gGGfNIMGFK95mxQ66SfAHtYm.jpg"}

I can access the properties in the client side but not on the server side.

Can someone help me to understand what's happening? Why can't I access my object properties?

The above comments are most likely correct. If img were an object then the console output would be more like Object {id: 42, path: "gGGfNIMGFK95mxQ66SfAHtYm.jpg"}. What you've posted is a string. — Reinstate Monica Cellio
– Reinstate Monica Cellio, Commented Jul 6, 2016 at 9:50

Mohit Bhardwaj · Accepted Answer · 2016-07-06 09:55:18Z

6

As others have pointed out, most probably img is in string form. You need to run JSON.parse() on it to convert it to an object, so you can access its properties.

Here I have written the JSON.parse() inside a check i.e. only when img is of type "string" should you parse it. But I think, you will always be getting img as a string, so you can simply parse it without the check.

exports.sample = function (req, res) {
    var images = req.query.images;
    images.forEach(function (img) {
        console.log(img);

        //Here, this code parses the string as an object
        if( typeof img === "string" )
          img = JSON.parse( img );

        console.log(img.path, img.id);
        console.log(img);
    });
    res.end();
};

edited Jul 6, 2016 at 9:55

answered Jul 6, 2016 at 9:47

Mohit Bhardwaj

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3 Comments

Mohit Bhardwaj Over a year ago

@belyid You were getting a string and not an object ( not arrays ) ;)

elreeda Over a year ago

@belyid if you are working with express you should add body.parser as a middlware so you dont need to write this on every request.

belyid Over a year ago

In this case I was getting an array with only one string. But it could be more than one string that needed to be parsed.

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