CODEWITHSUNDEEP
javascriptarrays
PythonSOS
PythonSOS

Reputation: 359

Finding total number of characters in array after reducing

How would I find the total number of characters (including spacing and commas) in the array after using .reduce?

Ex. Say I had an array, that when using .reduce((prev, curr) => [prev, ', ', curr]), would result in 

array: item1, item2, item3

And when I find the amount of characters, it would be 19 (without 'array: ').

Upvotes: 0

Views: 76

Answers (4)

Chris Wesseling
Chris Wesseling

Reputation: 6368

Do I understand the question correctly if that you want the sum of the lenghts of an array of strings?

// I would define the function sum as
const sum = (iterable, start = 0) => iterable.reduce((a, b) => a + b, start);
// then
let array = ['item1', 'item2', 'item3'];
// and we can sum their lengths like this
console.log(sum(array.map((s) => s.length)));
// but then we're off because you want a comma and a space between them all
// so we should start with 2 * (length of array - 1)
console.log(sum(array.map((s) => s.length), 2 * (array.length - 1)));
// iff we have a items at all ofcourse
array = [];
console.log(sum(array.map((s) => s.length),
  array.length ? 2 * (array.length - 1) : 0));

But really, the join().length solution others mentioned is cleverer.

Upvotes: 0

Marc
Marc

Reputation: 11613

Like this:

var sumCharLengths = ['alpha ',' beta ','gamma'].reduce((a, b) => a + b.length, 0);
  • a is your "accumulator" value
  • b is the current array item as the reducer "loops" over the array
  • 0 is the start value for your accumulator

More documentation here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce

Alternatively, without reduce(), you could just join() the array items and take the length of that result, e.g.:

var sumCharLengths = ['alpha ',' beta ','gamma'].join().length

Upvotes: 1

Shawn Yap
Shawn Yap

Reputation: 969

Here's one with .reduce()

const strLength = ["item1", "item2", "item3"].reduce((prev, curr) => `${prev}, ${curr}`).length

Upvotes: 1

Aravindan Venkatesan
Aravindan Venkatesan

Reputation: 628

I would suggest you do join method instead of reduce. For your case, 

let array = ['item1', 'item2', ' item3 '];
const strLength = array.join().length;

Upvotes: 1

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