I have nested arrays those the user made. I want a JavaScript code to access for example "g" element in it

var nestedArrays = [
  [a,b,c,d],
  [e,f,[
    g,h
  ]]
];

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in this example i can access "g" element using this code

var element = nestedarrays[2][1][1];

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BUT if "g" is nested in 100 of arrays i have to write a lot of square brackets as it

var g = nestedArrays[2][3][1][?][?].....[?];

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OR i don't know how much "g" is nested

IS there an easy code to get any element in the nested arrays with pure javascript or jquery ???

CodePudding user response：

We all know that array are zero-based.

In your first Example to access 'g' You need to access:

• the second position (index [1]) which is ['e','f',['g','h']]
• then access the third position (index [2]) which is ['g','h']
• finally the first position (index [0]) and you get 'g'.

var nestedArrays = [['a','b','c','d'],['e','f',['g','h']]];
let x = nestedArrays[1][2][0];
console.log(x); // g

So from that we can say that to access 'g'
We need to follow this road of indices [1,2,0]

var nestedArrays = [['a','b','c','d'],['e','f',['g','h']]];
let roadToG = [1,2,0];

for(let i = 0; i < roadToG.length; i  ){
    nestedArrays = nestedArrays[roadToG[i]];
}
console.log(nestedArrays); // g

BUT if "g" is nested in 100 of arrays i have to write a lot of square brackets as it var g = nestedArrays[2][3][1][?][?].....[?];

In case we want to access 'g' dynamically without hard code the road of indices; We must loop recursively in array till we find 'g', in looping we keep track of road

function loopRecursively( arr, x ,roadToX = []){
    if(JSON.stringify(arr).indexOf(x) == -1) return null; //in edge case where there is no x in array; we just return null!
    for ( let i = 0; i < arr.length; i   ) {
        if( arr[i] == x ){
            roadToX.push(i);
        } else if( Array.isArray( arr[i] ) && JSON.stringify(arr[i]).indexOf(x) != -1 ){
            roadToX.push(i);
            loopRecursively( arr[i] , x, roadToX);
        }
    }
    return roadToX;
}
let nestedArrays = [['a','b','c','d'],['e','f',['g','h']]];
console.log( loopRecursively( nestedArrays, 'g' ) ); // [1, 2, 0]

CodePudding user response：

If you're just trying to find a particular element you could flatten the array and find it that way.

var nestedArrays = [
  ['a','b','c','d'],
  ['e','f',[
    'g','h'
  ]]
];

const g = nestedArrays.flat(Infinity).find(x => x === 'g');

console.log(g);

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