Is it possible to modify the accumulator data type in the .reduce function?

Question

Is it possible to modify the accumulator data type in the .reduce function?

Recently, I've been attempting to transform a string into an array of numbers[], however, my lack of experience with TypeScript has led me to struggle with properly typing my code to satisfy the TypeScript compiler...

My objective is as follows:

matString.split(/[\n ]/).reduce((acc, cur, index) => acc[index] = Number(cur));

Despite numerous attempts at defining types, such as this one, I haven't been able to get it working :(

matString.split(/[\n ]/).reduce((acc: Array<number>, cur, index) => acc[index] = Number(cur)) as Array<number>;

For some background, this piece of code takes in a matrix as a string and I'm looking to convert it into an array for further processing. While I have faced similar challenges before and found workarounds, I am determined to grasp the fix this time.

If it helps clarify my issue, here is a snapshot of my code accompanied by the error reported by the compiler: code image with error

This forms part of my solution to the problem outlined in this exercise found on exercism.

javascript arrays string typescript reduce

Answer 1

Answer №1

Why bother with the .reduce method when you can simply map the split string to Number? No need for explicit typing in this case:

const result = matString
  .split(/[\n ]/)
  .map(Number);

If you do opt for the .reduce approach, make sure to use generics to specify the accumulator type and remember to return the accumulator within the callback function:

const result = matString.split(/[\n ]/).reduce<Array<number>>((acc, cur, index) => {
    acc[index] = Number(cur);
    return acc;
}, []);

For input consisting of a string containing numeric characters, consider matching those characters directly instead of splitting on spaces and newlines:

const result = matString
  .match(/\d+(?:\.\d+)?/g) // assuming there will always be at least one match
  .map(Number);

Answer 2

Why bother with the .reduce method when you can simply map the split string to Number? No need for explicit typing in this case:

const result = matString
  .split(/[\n ]/)
  .map(Number);

If you do opt for the .reduce approach, make sure to use generics to specify the accumulator type and remember to return the accumulator within the callback function:

const result = matString.split(/[\n ]/).reduce<Array<number>>((acc, cur, index) => {
    acc[index] = Number(cur);
    return acc;
}, []);

For input consisting of a string containing numeric characters, consider matching those characters directly instead of splitting on spaces and newlines:

const result = matString
  .match(/\d+(?:\.\d+)?/g) // assuming there will always be at least one match
  .map(Number);

Is it possible to modify the accumulator data type in the .reduce function?

Answer №1

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