Assistance with javascript algorithm

Question

I can't seem to understand why index is returning undefined. The goal is to place a number in a ordered array, in the correct position. I start by findind the position, but it's returning undefined.

var arr = [3,7,9,12,16,20,31,43,50,55];
var value;
var i=0;
var index;

value = Number(prompt("Enter a value [3,7,9,12,16,20,31,43,50,55]"));
document.write( arr+"<br>");

while(value > arr[i]){

    if (value < arr[i])
    {
        index=i;
    }
    i++;
}

document.write(index+"<br>");

for (i=arr.length-1 ; i>=index; i--){
     arr[i+1] = arr[i];
}

arr[index]=value;
document.write(arr+"<br>");

Nina Scholz · Accepted Answer · 2020-01-11 17:35:40Z

2

For example, if you select 9, the loop goes up to 7 and this is the last value where the while condition is true. The nested check is never reached.

For getting a result, you could take the loop and increment only the index an take the check outside and if the value is smaller or equal, take the index.

var arr = [3, 7, 9, 12, 16, 20, 31, 43, 50, 55];
var value;
var i = 0;
var index;

value = Number(prompt("Enter a value [3,7,9,12,16,20,31,43,50,55]"));
console.log(...arr);

while (value > arr[i]) i++;

if (value <= arr[i]) index = i;

console.log(index);

answered Jan 11, 2020 at 17:35

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Eric Martins Over a year ago

Thanks, finally i removed the if condition inside the while, leaving index = i;

Collectives™ on Stack Overflow

Assistance with javascript algorithm

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related