CODEWITHSUNDEEP
javascript
user86168
user86168

Reputation: 35

Updating value of multidimensional array of object

If I have array:

var arr = [
 {
  text: "something",
  child: [
   {
    text: "something child",
    child: [..]
   },..
  ]
 },..
];

Is ther any more efficient way exept rebuilding whole array with updated value by using for() to edit element when I have array of indexes:

var index = [0, 0];

to do this:

arr[0]["child"][0]["text"] = "updated value";

This is just small example but arr will be sometimes 1 level depth sometimes 12, etc. And value I need to update sometimes is in first level:

arr[0]["text"] = "updated value"

Upvotes: 2

Views: 2826

Answers (4)

Zorak
Zorak

Reputation: 709

In my opinion, this in quite unmaintainable and you should consider different data structure. However, you asked about this kind of solution. You can you eval(), which is quite working, even it is dangerous for production environment without additional security checks:

var arr = [{
    text: "something",
    child: [{
            text: "something child",
            child: [{
                text: "something child",
                child: [{
                    text: "something child",
                    child: []
                }]
            }, {
                text: "something child",
                child: []
            }]
        },
        {
            text: "something child",
            child: [{
                text: "something child",
                child: []
            }, {
                text: "something child",
                child: []
            }]
        }
    ]
}, {
    text: "something",
    child: [{
            text: "something child",
            child: [{
                text: "something child",
                child: [{
                    text: "something child",
                    child: []
                }]
            }, {
                text: "something child",
                child: []
            }]
        },
        {
            text: "something child",
            child: [{
                text: "something child",
                child: []
            }, {
                text: "something child",
                child: []
            }]
        }
    ]
}];
var ind = [0, 1, 0];
var setsomething = 2;

function setChild(ind) {
    var ev = "arr";
    for (var i = 0; i < ind.length; i++) {
        if (i + 1 < ind.length) {
            ev += '[' + ind[i] + ']["child"]';
        } else {
            ev += '[' + ind[i] + ']["text"]'
        }
    }
    ev += '=' + setsomething.toString() + ";";
    console.log(ev);
    console.log("original array");
    console.log(arr);
    eval(ev);
     console.log("Modified array");
    console.log(arr);
}
setChild(ind);

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386560

You could iterate the indices and update text property at the end.

function update(child, indices, value) {
    indices.reduce((o, i) => o.child[i], { child }).text = value;
}

var array = [{ text: "something", child: [{ text: "something child", child: [] }] }];

update(array, [0, 0], 'foo');

console.log(array);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 2

Ele
Ele

Reputation: 33726

A good alternative is using vanilla for-loop.

let arr = [ {  text: "something",  child: [   {    text: "something child",    child: []   }  ] }],
    index = [0, 0],
    current = undefined;

for(let i = 0; i < index.length; i++) {
  if (i === index.length - 1) current[index[i]].text = "Ele from Stack";
  else current = (current || arr)[index[i]].child;
}

console.log(arr);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 0

Zachary Oldham
Zachary Oldham

Reputation: 868

You are probably going to want a recursive method that accepts the array, the indexes, and the new value as input. If the index array is of length one, then it updates that element in the array. If it is not, then it calls the method using the child array at the element specified by the first element in the index array, the index array with its first element removed, and the new value.

Upvotes: 0

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