can't access property of json object

Question

I can't seem to reach my object variables, I'm probably just doing a dummy mistake somewhere. A console.log of my array of objects (pResult) look like this, first object expanded but they all look alike:

[Object, Object, Object, Object, Object, Object, Object, Object, Object]

0: Object
depTime: "2014-12-04 18:35"
destination: "Norsesund station"
nr: "562"
operator: "Västtrafik"
typText: "Buss"
__proto__: Object
1: Object
2: Object
3: Object
4: Object
5: Object
6: Object
7: Object
8: Object
length: 9
__proto__: Array[0]

I try to do this...

for (var i = 0; i <= pResult.length; i++) {
    var html =  html + '<tr>';
    var html =  html + '<td>';
    var html =  html + pResult[i].depTime;
    var html =  html + '</td>';
    var html =  html + '</tr>';
}

...but get hit with this error:

Uncaught TypeError: Cannot read property 'depTime' of undefined

According to your output, pResult.depTime is defined, but pResult[i].depTime is not. Am I missing something? — Phil Tune
– Phil Tune, Commented Dec 4, 2014 at 18:05
Just an aside: this has nothing to do with JSON; you're dealing with JavaScript objects, not textual notation that describes objects. (If your question dealt with parsing JSON text into objects, then the [json] tag would be appropriate.) — apsillers
– apsillers, Commented Dec 4, 2014 at 18:06

juvian · Accepted Answer · 2014-12-04 18:03:19Z

3

Change :

i <= pResult.length;

To:

i < pResult.length;

Array is 0 based indexed, so if it has length 3, you only have indexes 0,1,2

answered Dec 4, 2014 at 18:03

juvian

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2 Comments

bob-fornal Over a year ago

This is what I saw pResult does not exist for pResult[9] ... 9 being the length.

Matt Welander Over a year ago

thank you, works. will accept as soon as it lets me.

Kevin Ji · Accepted Answer · 2014-12-04 18:13:07Z

1

Instead of using a loop, you can simply use reduce:

var html = pResult.reduce(function(previousValue, currentValue) {
    return previousValue + '<tr><td>' + currentValue.depTime + '</td></tr>';
}, '');

Note that this only works on IE 9+ (but it works in all other modern browsers), so if you need to support older versions of IE, you can polyfill the method.

answered Dec 4, 2014 at 18:13

Kevin Ji

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Comments

Herbi Shtini · Accepted Answer · 2014-12-04 18:12:33Z

0

try this:

for (var i = 0; i < pResult.length; i++) {
        var html =   '<tr>';
            html +=  html + '<td>';
                html +=  html + pResult[i].depTime;
            html +=  html + '</td>';
        html +=  html + '</tr>';
}

The problem is you are loopin until arrays length but array start at 0 index so
if you have array
var pResult= [object,object,object];
pResult.length =3
pResult[3] doesnt exist so it is undefined.
NOTE dont recreate the variable when you just want to add text just add it to the existing one For example html+=" the added text"

answered Dec 4, 2014 at 18:12

Herbi Shtini

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