Problem with populating a 2D array?

Question

JavaScript

We get the text from the input, split it into an array by 1 element, put it into a two-dimensional array

var matrix=[];
    var key=prompt('enter key').split(''),
        text=input.value.toUpperCase().split(""); //console.log(text);
   // console.log(key); 
        for (var i=0; i<key.length; i++){
            matrix[i]=[];
            for(var j=0; j<input.length; j++){
                matrix[i][j]=text[j];
            }
        }

Answer 1

for (var j = 0; j < text.length; j++) {
  matrix[i][j] = text[j];
}