Proxy matrix with setter

proxy-set.js

const [width, height] = [10,10]   // 10x10 matrix

const element = (index) => index;

const array = Array.from({length: width * height}, (_,index) => index);

const handler = {
  get: (array, rowIndex) => {
    return new Proxy(array.slice(width * +rowIndex, width * (+rowIndex + 1)), Object.assign({array, rowIndex, width}, handler));
  },
  set: function(target, property, value, receiver) {
    let key = this.rowIndex * width + Number(property);
    this.array[key] = value;
  }
}

const matrix = new Proxy(array, handler);
matrix[3][5] = 3000;
console.log(matrix);  // index at 35 is 3000, setter worked...
console.log(matrix[3][5]); // but accessing through the proxy getter still returns 35? :\