push values into an array dynamically with javascript

Question

I'm have trouble finding a way to push values into an array dynamically. I have given the following situation:

var get_anchors= new Array('pitzel','mitzel','sizzle') 

current_anchor= pics[key].anchor; //has the value 'sizzle'

get_anchors[current_anchor].push(new Array('sizzle2','sizzle3'))

Javascript fails and says get_anchors[current_anchor] is undefined

How can I make get_anchors[current_anchor] work. Or is there a different way to get this done?

The desired result should look like 'pitzel','mitzel','sizzle'['sizzle2','sizzle3]

What exactly is this for? Arrays have numeric indexes, so of course get_anchors[current_anchor] is undefined, since current_anchor is not 0,1 or 2. What are you trying to accomplish? You will get better answers if you provide more information. — Felix Kling
– Felix Kling, Commented May 8, 2012 at 13:58
hi thanks for asking...in fact that is a part of a loop through a json object. i have some anchors very often with the same name and names of pictures associated with the anchor name. in the end i want to have an array[anchor] with anchors and its corresponding pictures...[anchorname][['picname1'],['picname2']] — Jurudocs
– Jurudocs, Commented May 8, 2012 at 14:08
So pitzel, pitzel and sizzle are anchors and sizzleX are picture names? Seems like you want a hash map instead of an array... — Felix Kling
– Felix Kling, Commented May 8, 2012 at 14:10

Felix Kling · Accepted Answer · 2012-05-08 14:11:58Z

4

Based on your comment it looks like you want a hash map instead of an array. You can use an object for this:

var anchors = {
    'pitzel': [],
    'mitzel': [],
    'sizzle': []
};

Then you can do:

anchors[current_anchor].push('sizzle2', 'sizzle3');

or assuming that anchors does not have a property with the value of current_anchor, simply assign a new array:

anchors[current_anchor] = ['fooX', 'fooY'];

Of course you can populate the object dynamically as well. Have a look at Working with Objects for more information.

answered May 8, 2012 at 14:11

Felix Kling

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9 Comments

Jurudocs Over a year ago

@unbeli yeah.. and in php this is pretty cool and works ;-P but in python that will work too...or not ?!

Felix Kling Over a year ago

@Jurudocs: It would not work in Python either. In PHP, arrays are powerful and can be used as both, numerical and associative arrays. That is not the case in other languages though. Python has dictionaries, JavaScript has objects, Java has HashMap, etc.

unbeli Over a year ago

In fact, Javascript arrays are objects too, can be (mis)used as dictionaries.

Felix Kling Over a year ago

@unbeli: Yes, but I think that is more confusing than helping for less experienced JS developers ;)

Jurudocs Over a year ago

@FelixKling you told me about the var anchors = { 'pitzel': [], 'mitzel': [], 'sizzle': [] }; Is it possible to generate the keys dynamically?

|

LukeGT · Accepted Answer · 2012-05-08 13:54:39Z

0

I'm not sure I understand what you're trying to do, but I think you're trying to insert a few elements after where another occurs. This will do the trick:

var get_anchors = [ 'pitzel', 'mitzel', 'sizzle' ];

current_anchor = get_anchors.indexOf(pics[key].anchor);
get_anchors.splice(current_anchor + 1, 0, 'sizzle2', 'sizzle3');

// get_anchors = [ 'pitzel', 'mitzel', 'sizzle', 'sizzle2', 'sizzle3' ]

answered May 8, 2012 at 13:54

LukeGT

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2 Comments

Jurudocs Over a year ago

hi thanks a lot...in the end i need a two-dimensional array like [ 'pitzel', 'mitzel', 'sizzle'['sizzle2', 'sizzle3']]

cliffs of insanity Over a year ago

@Jurudocs: You should show the desired result in your question so that we don't need to guess at what you want.

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