How do I loop through a numeric function parameter?

David Piper 0
Viewed 57

I'm having a lot of trouble figuring this one out. I have a function which passes value as a parameter, and I need a way to store each single digit that I'm passing in when I'm calling the function. I'm assuming I need to use a for loop and I can assign each digit to [i] but the logic isn't coming to me.

function assignValue(value) {
  for (let i = 0; i < value.length; i++) {
    // I'M LOST
  }
}
assignValue(123);
javascript
2 Answers

There are no "digits" in a value of type number, for the concept of "digits" you have to convert to string in the numbering system you want (for instance, base 10).¹ Once you've converted to string, you can loop through it with code like the code in your question, or more easily with a for-of loop:

function assignValue(value) {
    // Convert to string
    const str = String(value);
    // Loop through the string
    for (const char of str) {
        console.log(char);
    }
}
assignValue(123);

¹ It is possible to do this mathematically, by figuring out what the highest multiple of 10 you need is (100 in your case), and then working through by Math.floor(value / multiple), then doing value %= multiple and multiple /= 10, and continuing that while multiple >= 1:

function assignValue(value) {
    let multiple = 1;
    // Figure out where we need to start -- I'm sure there's a
    // clever mathematics way to do this rather than this brute
    // force approach
    while (multiple < value) {
        multiple *= 10;
    }
    // That took us too far, so:
    multiple /= 10;
    
    // Loop through
    while (multiple >= 1) {
        console.log(Math.floor(value / multiple));
        value %= multiple;
        multiple /= 10;
    }
}
assignValue(123);

But using a string is probably easier.

T.J. Crowder0

Another way to go about it, that's without using the for loop is to turn the number into an array of the digits

function assignValue(value) {
  return Array.from(String(value), Number);
}
console.log(assignValue(123))

Charles Kasasira0
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