CODEWITHSUNDEEP
javascript
marie_antoinette
marie_antoinette

Reputation: 181

Javascript: Get Length of a String without Length Propery, And with Slice

I know, it's a weird one! But why does this not work?

function getStringLength(string) {

  // see how many substrings > 0 can be built
  // log that number & return

  var subString = string.slice();
  var counter = 0;

  while (subString !== '') {
    counter++;
    subString = subString.slice(counter);
  }

  return counter;
}

var output = getStringLength('hello');

console.log(output); // --> expecting 5, but getting 3 (??)

I really want to do it with slice! The original challenge was to not use the length property, and I figured this out, which works fine:

function getStringLength(string) {

  var long = 0;

  while (string[long] !== undefined) {
    long++;
  }

  return long;
}

Upvotes: 4

Views: 603

Answers (4)

Naga Sai A
Naga Sai A

Reputation: 10975

To achieve expected result, use below option 

function getStringLength(arr){
  return arr.lastIndexOf(arr.slice(-1))+1
}

var output = getStringLength('hello');
console.log(output);

https://codepen.io/nagasai/pen/gGPWEE?editors=1111

Option2: As type of array is object,below option works too

function getStringLength(arr){
  return Object.keys(arr).pop()*1 + 1
}

var output = getStringLength('hello');
console.log(output);

https://codepen.io/nagasai/pen/PJZmgg?editors=1111

Check the below updated options to handle empty and numbers https://codepen.io/nagasai/pen/GMoQgy?editors=1111
https://codepen.io/nagasai/pen/YrweWr?editors=1111

Upvotes: 1

Marco de Zeeuw
Marco de Zeeuw

Reputation: 506

Perhaps a slightly shorter answer:

function getStringLength(string) {
  var counter = 0;
  while (string.slice(counter)) {
    counter++;
  }

  return counter;
}

var outputHello = getStringLength('hello');
console.log(outputHello); // 5

var outputEmpty = getStringLength('');
console.log(outputEmpty); // 0

Upvotes: 0

Nicholas Tower
Nicholas Tower

Reputation: 84982

The problem is the code substring.slice(counter) First time, you chop off 1 character. Then you chop off 2 characters from the already-chopped substring. Either chop off 1 at a time, or chop off the increasing amount from the original string. So that's either substring.slice(1) or string.slice(counter)

function getStringLength(string) {

  // see how many substrings > 0 can be built
  // log that number & return

  var subString = string.slice();
  var counter = 0;

  while (subString !== '') {
    counter++;
    subString = substring.slice(1);
  }

  return counter;
}

var output = getStringLength('hello');

console.log(output);

Upvotes: 4

marvel308
marvel308

Reputation: 10458

you were mutating your string, this should work for you

function getStringLength(string) {

  // see how many substrings > 0 can be built
  // log that number & return

  var subString = string.slice();
  var counter = 0;

  while (subString !== '') {
    counter++;
    subString = subString.slice(1);
  }

  return counter;
}

var output = getStringLength('hello');

console.log(output); // 5

The main difference was that I was doing

subString = subString.slice(1);

instead of

subString = subString.slice(counter);

which always decreased length by 1

Upvotes: 6

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