Javascript Object Access

Question

I am using a Comet Push Engine called APE (Ajax Push Engine) and whenever I receive a realtime event I receive it in an javascript object called 'raw'.

So if for example if the raw object contains a 'location' value, I can print 'raw.location' and it will give me the value,

alert(raw.location);

So I have another object called currentSensor, which contains a value like this (in my example it would contain the string 'location'):

currentSensor.value

How do I programmatically use the currentSensor.value variable to access the 'raw' object? I have tried this:

var subsensor = currentSensor.sensorKey;

and then

alert(raw.subsensor);

But I keep getting undefined because the raw object doesn't contain a key called "subsensor" its actually "location". I hope this makes sense!

Thanks!

Quentin · Accepted Answer · 2010-12-27 18:10:34Z

5

When using dot-notation, you use a literal property name. If you want to use a string, use square bracket notation.

foo.bar === foo['bar'];

Strings can be variables.

baz = 'bar';
foo.bar === foo[baz];

answered Dec 27, 2010 at 18:10

Quentin

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Jan · Accepted Answer · 2010-12-27 18:10:39Z

3

like this:

console.log(raw[currentSensor.value]);

answered Dec 27, 2010 at 18:10

Jan

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Comments

Alin P. · Accepted Answer · 2010-12-27 18:22:16Z

1

Here you go:

alert(raw[subsensor]);

The dot syntax cannot help you when you need to access variable indexes. You need to use the array access method.

Note: The dot access method is just syntactic sugar and is not really needed in any place, but it is useful for code readability.

For your entertainment:

"1,2,3"["split"](",")["join"]("|")

edited Dec 27, 2010 at 18:22

answered Dec 27, 2010 at 18:11

Alin P.

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3 Comments

Doug Molineux Over a year ago

Thank you guys! I guess I'll go with this one since it was the quickest :)

Quentin Over a year ago

By 'quickest' do you mean 'at the top when you sort with newest first'? :)

Doug Molineux Over a year ago

Right, first one listed, but thank you all of your advice was helpful, I upvoted each of them

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