How to pass variables as the name of array into function in Javascript

Question

From my DOM element, I let the user choose a state.

In my code I go:

 var State = $("select[name=state1]").val();

So if AZ was selected, the ouput would be State == "AZ"

Then I have arrays for every state so for example:

var AZ =[[1],[2]];

And I fill each array with some data. Then I try to do a calculation that looks like this:

var ABC = 25 * State[0][1];

However, the variable state isn't an array. I want state replaced by the chosen one, for example it might be AZ so I actually want to calculate...

 var ABC = 25 * AZ[0][1];

Any ideas on how I can pass the value of State into last equation automatically?

J. Titus · Accepted Answer · 2016-02-26 04:34:38Z

1

I suggest assigning your state values a little differently:

var states = {
    AZ: [[1],[2]],
    //and so on
};

Then you can do

var ABC = 25 * states[State][0][1];

answered Feb 26, 2016 at 4:34

J. Titus

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11 Comments

Badrush Over a year ago

I dont understand what AZ: [[1][2]] does. State returns "AZ" from the DOM and then I want to call element AZ[1][2] by typing State[1][2]

J. Titus Over a year ago

Basically the bottommost expression expands to 25 * the 2nd element of the array associated with attribute "AZ" of states (25 * 2)

J. Titus Over a year ago

AZ is an array, that contains 2 arrays, with one element each. What were you expecting?

J. Titus Over a year ago

So, {AZ: [[1,2,3],[4,5,6]]}?

J. Titus Over a year ago

I think you should read about how objects and arrays work in JavaScript. Let's say you want to change the 4 to a 7. You would do states.AZ[1][0] = 7; or states["AZ"][1][0] = 7;

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artm · Accepted Answer · 2016-02-26 04:31:53Z

1

Change your state to be an object to contain state arrays:

var state = { AZ : [[1],[2]], OS : [[3], [4]] };
var abc = 25 * state["AZ"][0]

answered Feb 26, 2016 at 4:31

artm

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12 Comments

Badrush Over a year ago

What is OS? and what does the : do here?

J. Titus Over a year ago

I'll take a guess and say it's an arbitrary state abbreviation data point used just as an example... And : assigns the array to the object's named data point.

artm Over a year ago

@Badrush Just like jTitus said, 'OS' could be anything, just an example of another state, and : is how you assign values to object's properties.

Badrush Over a year ago

Okay, but if I am defining state as var State = $("select[name=state1]").val(); I cannot make state a bunch of arrays. I basically get a string from the user, which I need to use to find the array whose name matches that string.

artm Over a year ago

@Badrush stackoverflow.com/questions/966225/…

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