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Utils for JavaScript - what do you use regularly?

Dragoljub Bogićević on March 21, 2020

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 c...

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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...