Getting a Parameter and Using it as an Array Name in Javascript

Question

Let's say I have a bunch of arrays named a=[], b=[], c=[], d=[], and so on. A Table is shown to the client and depending on the cell that the client clicks, we do operations to the specific array made for that cell. The code explains what I mean in a better way. I would be thankful if anyone helps. HTML:

<td id="block1" class="blocks" onclick="markNLock('a',this)" onmouseover="setMouseOverColor(this)" onmouseout="setMouseOutColor(this)">

Js:

function markNLock(idx, mark) {
    for(var i=0; i<Matrix.length; i++)
    {
        Matrix[i] += idx[i];
        console.log(idx[i]);
    }
}

your problems are caused by using mid 90's style inline event handlers. If you write your code using addEventListener instead this problem won't happen. — Alnitak
– Alnitak, Commented Oct 12, 2020 at 16:05
Try telling what exactly is the problem and Half the stuff is not told — Alpha Wolf Gamer
– Alpha Wolf Gamer, Commented Oct 12, 2020 at 16:06
@AlphaWolfGamer the problem is obvious - the OP is passing a string for the array name, and wants to access the array of that particular name. — Alnitak
– Alnitak, Commented Oct 12, 2020 at 16:08
Why don't you remove the string tag and instead pass in a instead of "a". Problem solved — Alpha Wolf Gamer
– Alpha Wolf Gamer, Commented Oct 12, 2020 at 16:10
NB: having a bunch of arrays of (presumed) identical purpose but with different names is an indication of poor design. Variable names are not the way to differentiate items like that - they should either be a two-D array, or an object where the keys are the "identifier" and the array is the value. — Alnitak
– Alnitak, Commented Oct 12, 2020 at 16:10

Alnitak · Accepted Answer · 2020-10-12 16:59:30Z

1

Notwithstanding the other advice I've given, the most expedient fix for your problem is not to use separate arrays, but to use your strings a, b etc as keys into the lookup matrix:

const game_matrix = {
  'a': [1, 1, 0, 0, 1, 0, 0, 0],
  'b': [0, 1, 0, 0, 0, 1, 0, 0],
  ...
}

and you can then use your string parameter as an index into that object:

Matrix[i] += game_matrix[idx][i];

answered Oct 12, 2020 at 16:59

Alnitak

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