How to create and populate two dimentional array inside ES6 class constructor

Question

I want to initialize and populate a two-dimensional array, but my solution doesn't seem to work. It only returns a function, not a value.

class Board{
    constructor(width,height,cols,rows)
    {
        this.width=width;
        this.height=height;
        this.cols=cols;
        this.rows=rows;
        this.array= function(){
            let array=[];
            for(let i=0;i<this.cols;i++)
            {
                array[i]=[];
                for(let j=0;j<this.rows;j++){
                    array[i][j]=0;
                }
            }
            return array;
        }
    }

Barmar · Accepted Answer · 2019-06-01 16:44:11Z

4

There's no need for the inner function, just populate the array and assign it to the property.

class Board {
  constructor(width, height, cols, rows) {
    this.width = width;
    this.height = height;
    this.cols = cols;
    this.rows = rows;
    let array = [];
    for (let i = 0; i < this.cols; i++) {
      array[i] = [];
      for (let j = 0; j < this.rows; j++) {
        array[i][j] = 0;
      }
    }
    this.array = array;
  }
}

const b = new Board(2, 3, 4, 5);
console.log(b.array);

answered Jun 1, 2019 at 16:44

Barmar

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Comments

moodpulse · Accepted Answer · 2019-06-01 16:46:38Z

0

Can be easier

class Board {
  constructor(width, height, cols, rows) {
    this.width = width;
    this.height = height;
    this.cols = cols;
    this.rows = rows;
    this.array = [];
    for (let i = 0; i < this.cols; i++) {
      this.array.push(new Array(this.rows).fill(0));
    }
  }

answered Jun 1, 2019 at 16:46

moodpulse

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Comments

Code Maniac · Accepted Answer · 2019-06-01 16:46:58Z

0

You can directly put values on property no need to function

class Board {
  constructor(width, height, cols, rows) {
    this.width = width;
    this.height = height;
    this.cols = cols;
    this.rows = rows;
    let array = new Array(this.cols).fill(0).map(val=> new Array(this.rows).fill(0))
    this.array = array;
  }
}

const b = new Board(2, 3, 4, 5);
console.log(b.array);

answered Jun 1, 2019 at 16:46

Code Maniac

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Comments

Amith · Accepted Answer · 2019-06-01 16:51:35Z

0

this.array= function(){
    let array=[];
    for(let i=0;i<this.cols;i++)
    {
        array[i]=[];
        for(let j=0;j<this.rows;j++){
            array[i][j]=0;
        }
    }
    return array;
}

This just creates a function named this.array.

If you want this.array to hold the return value, call the function there itself.

this.array= (function(){
    let array=[];
    for(let i=0;i<this.cols;i++)
    {
        array[i]=[];
        for(let j=0;j<this.rows;j++){
            array[i][j]=0;
        }
    }
    return array;
})();

answered Jun 1, 2019 at 16:51

Amith

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