How to handle eslint no-param-reassign rule in Array.prototype.reduce() functions

Question

I\'ve recently added the eslint rule no-param-reassign.

However, when I use reduce to build out an object (empty object as initialValue), I find myself need

Answer 1

I just wrap the reduce functions in a lint rule disable block, ie:

/* eslint-disable no-param-reassign */
const newObject = ['a', 'b', 'c'].reduce((result, item, index) => {
  result[item] = index;
  return result;
}, {});
/* eslint-enable no-param-reassign */

Answer 2

One solution would be to leverage the object spread operator

const newObject = ['a', 'b', 'c'].reduce((result, item, index) => ({
  ...result,
  [item]: index, 
}), {});

Answer 3

Well, you could do (result, item) => Object.assign({}, result, {[item]: whatever}) to create a new object on every iteration :-)

If you want to trick the linter, you could use => Object.assign(result, {[item]: whatever}) (which does the same as your current code but without an explicit assignment), but yeah I guess you should simply disable that rule.