Dragoljub Bogićević

Posted on Mar 21, 2020

Utils for JavaScript - what do you use regularly?

#discuss #javascript #typescript

Recently, I started working on my own utils set of JavaScript functions that can be used on every day basis.

This is the current list (full docs can be found here):

Compare objects
Compare arrays
Check if an array or an object is empty
Make array unique
Get min value of an array of numbers
Get max value of an array of numbers
Check if variable is an integer
Create random number
Cache function result
Calculate how much time a function takes to run

Which functions do you use, in which cases, please comment down bellow, certainly I would consider all suggestions and add new functions as part of npm package.

Thank you for reading and all suggestions!

Top comments (5)

Heiker • Mar 21 '20

map and filter for objects. I've done this a couple of times.

const Obj = {
  map(fn, data) {
    let result = {};
    for (let [key, value] of Object.entries(data)) {
      result[key] = fn(value, key, data);
    }

    return result;
  },
  filter(fn, data) {
    let result = {};
    for (let [key, value] of Object.entries(data)) {
      if(fn(value, key, data)) {
        result[key] = value;
      }
    }

    return result;
  }
};

I've also used a "better" typeof.

function what_is(arg) {
  const is = Object.prototype.toString.call(arg);

  return {
    val: () => is,
    object: () => is == '[object Object]',
    array: () => is == '[object Array]',
    promise: () => is == '[object Promise]',
    undefined: () => is == '[object Undefined]',
    null: () => is == '[object Null]',
    number: () => is == '[object Number]',
    func: () => is == '[object Function]'
  };
}

bravemaster619 • Mar 21 '20 • Edited

Safe number for price calculations.

const safeNumber = (num, defaultValue = 0, allowNegative = false) => {
  if (!num) {
    num = 0;
  }
  num = Number(num)
  if (isNaN(num)) {
    if (defaultValue === undefined) {
      console.log(num)
      throw new Error('Given argument is NaN')
    } else {
      return defaultValue
    }
  }
  if (num === Infinity) {
    if (defaultValue === undefined) {
      console.log(num)
      throw new Error('Given argument is infinity')
    } else {
      return defaultValue
    }
  }
  if (!allowNegative && num < 0) {
    if (defaultValue === undefined) {
      console.log(num)
      throw new Error('Given argument is negative')
    } else {
      return defaultValue
    }
  }
  return num
}

Pacharapol Withayasakpunt • Mar 22 '20 • Edited

Sort anything, base on MongoDB order with dotProp
Stable JSON.stringify, stringifying classes, stable hash
distinctBy, mapAsync, chuck

export async function mapAsync<T, R = T> (
  arr: T[],
  cb: (el: T, i: number, a0: T[]) => Promise<R>,
): Promise<R[]> {
  return Promise.all(arr.map(async (el, i, a0) => {
    return await cb(el, i, a0)
  }))
}

export function distinctBy<T> (arr: T[], k: string, undefinedIsDistinct?: boolean): T[] {
  const arrK = arr.map((a) => hash((a as any)[k]))
  return arr.filter((a, i) => {
    const aK = (a as any)[k]
    if (aK === undefined) {
      return !!undefinedIsDistinct
    } else {
      return arrK.indexOf(hash(aK)) === i
    }
  })
}

export function * chunk<T> (arr: T[], n: number) {
  for (let i = 0; i < arr.length; i += n) {
    yield arr.slice(i, i + n)
  }
}

Are you trying to create next lodash or something?

Tim Anthony Manuel • Mar 21 '20 • Edited

Hmm... What about..

[array].every(item=>[array2].includes(item))

Dragoljub Bogićević • Mar 21 '20 • Edited

Good one! Added to version 1.0.9...

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Utils for JavaScript - what do you use regularly?

Top comments (5)

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