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JS Basic Question


Drongo_III
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Go to solution Solved by Jacques1,

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I have a really basic question.

 

Why is it you can't create a multidimensional array like this in javascript:

t['key1']['key2'] = 123;

I have worked with JS for a long time and I get the proper form is to do something like:

t['key1'] = {'key2' : 123}

 But I'm just wondering why it's not possible to do the first version?  Is it because JS doesn't know what to cast the 'key2' to?

 

Thanks,

 

Drongo

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This array feature which you appearently know from PHP is actually very exotic and really only makes sense in the super-sloppy PHP philosophy.

 

Technically speaking, you simply cannot apply the index operator to the empty value t['key1']. There's no such thing as null['key2']. If you try this in Ruby, your script will blow up with an error message. The same is true for Python. The only reason why PHP doesn't blow up is because it's specifically designed to accept errors. Instead of telling you to fix your code, it will guess what you mean and create a new subarray for you.

 

So this isn't how languages normally works. It's a PHPism.

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This array feature which you appearently know from PHP is actually very exotic and really only makes sense in the super-sloppy PHP philosophy.

 

Technically speaking, you simply cannot apply the index operator to the empty value t['key1']. There's no such thing as null['key2']. If you try this in Ruby, your script will blow up with an error message. The same is true for Python. The only reason why PHP doesn't blow up is because it's specifically designed to accept errors. Instead of telling you to fix your code, it will guess what you mean and create a new subarray for you.

 

So this isn't how languages normally works. It's a PHPism.

 

Thanks Jacques. You're quite right, I'm a php developer first and didn't realise this was a feature particular to php. Makes much more sense now.

 

Drongo

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