How to access and store an array of objects in JavaScript

Question

I have these objects that are stored in array :

var current = [{1:{X:"",Y:""},2:{X:"",Y:""},3:{X:"",Y:""}},
           {1:{X:"",Y:""},2:{X:"",Y:""},3:{X:"",Y:""}},
           {1:{X:"",Y:""},2:{X:"",Y:""},3:{X:"",Y:""}}
           ];

What I want is to store them dynamically and access them dynamically after passing the objects value in a function.

function getXAxis(num){
//any
}

function getYAxis(num){
//any
}

trial1a.X = getXAxis(current[0][1].X);
trial1a.Y = getYAxis(current[0][1].Y);
trial2a.X = getXAxis(current[0][2].X);
trial2a.Y = getYAxis(current[0][2].Y);
trial3a.X = getXAxis(current[0][3].X);
trial3a.Y = getYAxis(current[0][3].Y);
trial1b.X = getXAxis(current[1][1].X);
trial1b.Y = getYAxis(current[1][1].Y);

What is the best way to access current values and store them dynamically as well

It's not clear to me what the issue is. You are already accessing the values in `current`. — Felix Kling, Oct 29 '15 at 03:07
Please note in your definition you're using capital `"X"`, `"Y"` but when trying to lookup you're using lower `"x"`, `"y"` — Paul S., Oct 29 '15 at 03:07
Then use a variable instead of any of the numbers. E.g. `current[i]`, where `i` gets its value from wherever. Is that what you are asking for? If you have ever iterated over an array with a `for` loop, you know how to access an array "dynamically". — Felix Kling, Oct 29 '15 at 03:09
Regarding adding: [Add new object to array](http://stackoverflow.com/q/9543805/218196). — Felix Kling, Oct 29 '15 at 03:10
"dynamically" in the sense that I don't need to declare trial1a.x... one by one — ajbee, Oct 29 '15 at 03:13
So you actually want to *create variables* dynamically? That's almost always a bad idea. You should have an array of `trial` elements instead (but then again you already have an array of objects). Not really sure where you are going with all of this.... maybe you are rather looking for `.map`? https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map — Felix Kling, Oct 29 '15 at 03:16

Steven Moseley · Accepted Answer · 2015-10-29T03:33:30.140

1

I think what you want is to have your trials be dynamically generated?

Something like this should do what you want:

var trials = [];
for (var i = 0; i < current.length; i++) {
    trials[i] = {};
    for (var j in current[i]) {
        trials[i][j] = {
            X: getXAxis(current[i][j].X),
            Y: getYAxis(current[i][j].Y)
        };
    }
}

edited Oct 29 '15 at 03:33

answered Oct 29 '15 at 03:18

Steven Moseley

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Use a normal `for` loop to iterate over the array. – Felix Kling Oct 29 '15 at 03:21
`for... in` works for arrays, too, but changed, nevertheless – Steven Moseley Oct 29 '15 at 03:22
what is trials[i] = trials[i] || {}; for? – ajbee Oct 29 '15 at 03:27
@ThomasM.- That's initialization of the index - ensuring that the index is set in the trials array before it's accessed when we set `trials[i][j]`. If you don't initialize it, JS will throw an error. – Steven Moseley Oct 29 '15 at 03:30
@ThomasM.- In thinking about it, the conditional isn't necessary. Changed it to just set the index to an object. – Steven Moseley Oct 29 '15 at 03:34

score 0 · Answer 2 · answered Oct 29 '15 at 03:47

I guess I know what you are looking for..

var root = {};
function setValueInDeepStructure(value, path, tree) {  
  var thisStep = path.shift();
  if (path.length == 0) {
    tree[thisStep] = value;
  } else {
    if (!tree[thisStep]) {
      tree[thisStep] = {};
    }

    setValueInDeepStructure(value, path, tree[thisStep]);
  }
}

function getValueFromDeepStructure(path, tree) {
  var thisStep = path.shift();
  if (path.length == 0)
    return tree[thisStep];
  else
    return getValueFromDeepStructure(path, tree[thisStep]);
}

setValueInDeepStructure({x: 3, y: 5}, [0,1,5,6], root);
setValueInDeepStructure(7, [0,1,5,6,'x'], root);

getValueFromDeepStructure([0,1,5,6], root) // => {x:7, y:5}

How to access and store an array of objects in JavaScript

2 Answers2