Orkhan Jafarov

Posted on Jan 18, 2021 • Edited on Feb 14, 2021

🦸‍♂️ 11 JavaScript Tips and Tricks to Code Like A Superhero (Vol.2)

#javascript #beginners #webdev #tutorial

Hi JS-heroes! Finally done with this new article! Let's go ahead ✨

1. Generate a list with random numbers

We need A LOT of fake data, for different reasons. So here's a way to do that gently.

Array.from({ length: 1000 }, Math.random)
// [ 0.6163093133259432, 0.8877401276499153, 0.4094354756035987, ...] - 1000 items

2. Generate a list with numbers

Yep, just one more trick to generate a list with numbers.

Array.from({ length: 1000 }, (v, i) => i)
// [0, 1, 2, 3, 4, 5, 6....999]

1-2 edited. Thanks to Andrew Courtice

3. Convert RGB → HEX

Convert your RGB to HEX without any libs!

const rgb2hex = ([r, g, b]) =>
  '#' + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).substr(1);

rgb2hex([76, 11, 181]);
// #4c0bb5

4. Convert HEX → RGB

What's about convert it back?! Here's a nice way to implement that.

const hex2rgb = hex =>
  [1, 3, 5].map((h) => parseInt(hex.substring(h, h + 2), 16));

hex2rgb("#4c0bb5");
// [76, 11, 181]

5. Odd or Even

Another yet odd/even checking.

const value = 232;  

if (value & 1) console.log("odd");
else console.log("even");
// even

6. Check valid URL

I guess most of you use this way to validate URL, but anyway. Let's share it

const isValidURL = (url) => {
  try {
    new URL(url);
    return true;
  } catch (error) {
    return false;
  }
};

isValidURL("https://dev.to");
// true

isValidURL("https//invalidto");
// false

7. N something ago

Sometimes you need something to print a date to 6 minute(s) ago, but don't want to import monster-size libs. Here's a small snippet that does it, easily modify it as you wish and go ahead.

const fromAgo = (date) => {
  const ms = Date.now() - date.getTime();
  const seconds = Math.round(ms / 1000);
  const minutes = Math.round(ms / 60000);
  const hours = Math.round(ms / 3600000);
  const days = Math.round(ms / 86400000);
  const months = Math.round(ms / 2592000000);
  const years = Math.round(ms / 31104000000);

  switch (true) {
    case seconds < 60:
      return `${seconds} second(s) ago"`;
    case minutes < 60:
      return `${minutes} minute(s) ago"`;
    case hours < 24:
      return `${hours} hour(s) ago"`;
    case days < 30:
      return `${days} day(s) ago`;
    case months < 12:
      return `${months} month(s) ago`;
    default:
      return `${years} year(s) ago`;
  }
};

const createdAt = new Date(2021, 0, 5);
fromAgo(createdAt); // 14 day(s) ago;

8. Generate path with params

We work a lot with routes/paths and we always need to manipulate them. When we need to generate a path w/ params to push browser there, generatePath helps us!

const generatePath = (path, obj) =>
    path.replace(/(\:[a-z]+)/g, (v) => obj[v.substr(1)]);

const route = "/app/:page/:id";
generatePath(route, {
  page: "products",
  id: 85,
});
// /app/products/123

9. Get params from path

Yes! Now we need to get our params back. Also, you can pass serializer to parse your data gently.

const getPathParams = (path, pathMap, serializer) => {
  path = path.split("/");
  pathMap = pathMap.split("/");
  return pathMap.reduce((acc, crr, i) => {
    if (crr[0] === ":") {
      const param = crr.substr(1);
      acc[param] = serializer && serializer[param]
        ? serializer[param](path[i])
        : path[i];
    }
    return acc;
  }, {});
};

getPathParams("/app/products/123", "/app/:page/:id");
// { page: 'products', id: '123' }

getPathParams("/items/2/id/8583212", "/items/:category/id/:id", {
  category: v => ['Car', 'Mobile', 'Home'][v],
  id: v => +v
});
// { category: 'Home', id: 8583212 }

10. Generate path with query string

Of course, we work with paths and we need to generate path with query too.

const generatePathQuery = (path, obj) =>
  path +
  Object.entries(obj)
    .reduce((total, [k, v]) => (total += `${k}=${encodeURIComponent(v)}&`), "?")
    .slice(0, -1);

generatePathQuery("/user", { name: "Orkhan", age: 30 }); 
// "/user?name=Orkhan&age=30"

11. Get params from query string

Now it's a time to get params from query string.

const getQueryParams = url =>
  url.match(/([^?=&]+)(=([^&]*))/g).reduce((total, crr) => {
    const [key, value] = crr.split("=");
    total[key] = value;
    return total;
  }, {});

getQueryParams("/user?name=Orkhan&age=30");
// { name: 'Orkhan', age: '30' }

Conclusion

Try to understand how everything works and keep your code nice/clean.

Take your JS-hero's skills and save the world! ✨🦸‍♂️ ✨

Save and contribute tips/tricks on github code-like

Top comments (21)

Médéric Burlet • Jan 19 '21

One that I love is this:

const someVar = null
const myValue = someVar || "default text"

The or operator works the same as an elvis operator.

This is useful if you want to display a default value when you can't get data from an api or if some data is null for a key.

This can be chained with objects

const someVar = {foo: {bar: null}}
const myValue = someVar?.foo?.bar || "default text"

Lesley van der Pol • Jan 21 '21 • Edited

Love this one too, it's also useful to prevent errors when destructuring something that could be undefined:

const { foo, bar } = couldBeUndefined || {};

This can prevent errors such as "Cannot read foo of undefined".

Micha • Jan 19 '21

With ES2021 we have ||= :)
Which makes the syntax even cooler

I made a video about new features here:
youtu.be/hxmFYToenxE

Médéric Burlet • Jan 19 '21

True but not fully supported yet

Micha • Jan 19 '21

With the right babelJS version it is ;)

Médéric Burlet • Jan 19 '21

And then you're bringing big pieces of extra code for not much 😉 good way to slow websites.

Grzesiek Dunin-Ślęczek • Jan 24 '21

I would say that developer convenience is more than a lot. Also, few bytes of code for polyfill, definitely will not slow down the website.

Médéric Burlet • Jan 24 '21

I tend to think of client first. UX is more important than writing one word less. for a developer. between users having slow internet speeds, limited networks and not the greatest machines bringing one poly-fill here and there vs zero can make a huge difference. If you are making something just for you or limited public then why not but the difference in code between the statement I used vs using ||= is not that big that it would justify using a poly-fill on my end. If we were talking about a promise polyfill for example that would be a different matter.

But in the end everyone codes differently. So whatever suits your coding style then use it.

Andrew Courtice • Jan 18 '21

Great article!

It's worth noting that the first 2 examples can be written ever so slightly shorter using Array.from as the Array.from method supports a mapping function as it's second argument.

Here's the first example using Array.from:

Array.from({ length: 1000 }, Math.random)

And the second example:

Array.from({ length: 1000 }, (v, i) => i)

Orkhan Jafarov • Jan 18 '21

You're right! This way is slightly shorter! I'll replace mine with them
Thank you mate!

ogheneovo12 • Jan 20 '21

Here is what I use

[...Array(1000).keys()]

Médéric Burlet • Jan 19 '21

Array from for the win I had an issue with array fill hahaha

How Array.fill can break arrays!

Médéric Burlet ・ Oct 7 '20 ・ 2 min read

#javascript #beginners #webdev

Renzo • Jan 22 '21

In the case of no. 5: I would always chose readability over bitwise trickery, when not absolutely necessary. So instead of bitwise AND, just use modulo;

const value = 232;  

if (value % 2) console.log("odd");
else console.log("even");
// even

Chad Gauthier • Jan 25 '21

Hey just a small improvement to N something ago example to show/hide plural.

const fromAgo = (date) => {
  const ms = Date.now() - date.getTime();
  const seconds = Math.round(ms / 1000);
  const minutes = Math.round(ms / 60000);
  const hours = Math.round(ms / 3600000);
  const days = Math.round(ms / 86400000);
  const months = Math.round(ms / 2592000000);
  const years = Math.round(ms / 31104000000);
  let ago;

  if(seconds < 60)
    ago = `${seconds} second"`;
  else if (minutes < 60)
    ago = `${minutes} minute`;
  else if (hours < 24)
    ago = `${hours} hour`;
  else if (days < 30)
    ago = `${days} day`;
  else if (months < 12)
    ago = `${months} month`;
  else
    ago = `${years} year`;

  const isSingular = ago.indexOf("1 ") === 0;

  ago += isSingular ? " ago" : "s ago";
  return ago;
}

const createdAt = new Date(2021, 0, 5);
fromAgo(createdAt); // 14 days ago

Fedor Vlasenko • Jan 27 '21

const generatePathQuery = (path, obj) =>`${path}?${new URLSearchParams(obj).toString()}`;
const link = generatePathQuery("/user", { name: "Orkhan", age: 30 });
console.log(link);

Joel D Souza • Jan 21 '21

case days < 30:
      return `${days} day(s) ago`;

This will not work for months with 31 days.

Orkhan Jafarov • Jan 21 '21 • Edited

It's a just simple version for that formatter. That's why it shows average time.
But it's okay with 31 days. If it's more than 30 days then 1 month;

example

new Date(2021, 0, 31); // now - 2021-01-30T20:00:00.000Z
const createdAt = new Date(2021, 0, 1); // 2020-12-31T20:00:00.000Z
fromAgo(createdAt); // 1 month(s) ago