7 Shorthand Optimization Tricks every JavaScript Developer Should Know 😎

Every language has its own quirks and JavaScript, the most used programming language, is no exception. This article will cover a plethora of JavaScript Shorthand Optimization tricks that can help you write better code, and also make sure this is NOT your reaction when you encounter them:

1. Multiple string checks

Often you might need to check if a string is equal to one of the multiple values, and can become tiring extremely quickly. Luckily, JavaScript has a built-in method to help you with this.

// Long-hand
const isVowel = (letter) => {
  if (
    letter === "a" ||
    letter === "e" ||
    letter === "i" ||
    letter === "o" ||
    letter === "u"
  ) {
    return true;
  }
  return false;
};

// Short-hand
const isVowel = (letter) =>
  ["a", "e", "i", "o", "u"].includes(letter);

2. For-of and For-in loops

For-of and For-in loops are a great way to iterate over an array or object without having to manually keep track of the index of the keys of the object.

For-of

const arr = [1, 2, 3, 4, 5];

// Long-hand
for (let i = 0; i < arr.length; i++) {
  const element = arr[i];
  // ...
}

// Short-hand
for (const element of arr) {
  // ...
}

For-in

const obj = {
  a: 1,
  b: 2,
  c: 3,
};

// Long-hand
const keys = Object.keys(obj);
for (let i = 0; i < keys.length; i++) {
  const key = keys[i];
  const value = obj[key];
  // ...
}

// Short-hand
for (const key in obj) {
  const value = obj[key];
  // ...
}

3. Falsey checks

If you want to check if a variable is null, undefined, 0, false, NaN, or an empty string, you can use the Logical Not (!) operator to check for all of them at once, without having to write multiple conditions. This makes it easy to check if a variable contains valid data.

// Long-hand
const isFalsey = (value) => {
  if (
    value === null ||
    value === undefined ||
    value === 0 ||
    value === false ||
    value === NaN ||
    value === ""
  ) {
    return true;
  }
  return false;
};

// Short-hand
const isFalsey = (value) => !value;

4. Ternary operator

As a JavaScript developer, you must have encountered the ternary operator. It is a great way to write concise if-else statements. However, you can also use it to write concise code and even chain them to check for multiple conditions.

// Long-hand
let info;
if (value < minValue) {
  info = "Value is too small";
} else if (value > maxValue) {
  info = "Value is too large";
} else {
  info = "Value is in range";
}

// Short-hand
const info =
  value < minValue
    ? "Value is too small"
    : value > maxValue ? "Value is too large" : "Value is in range";

5. Function calls

With the help of the ternary operator, you can also determine which function to call based on conditions.

IMPORTANT SIDE-NOTE: The call signature of the functions must be the same, else you risk running into an errors

function f1() {
  // ...
}
function f2() {
  // ...
}

// Long-hand
if (condition) {
  f1();
} else {
  f2();
}

// Short-hand
(condition ? f1 : f2)();

6. Switch shorthand

Long switch cases can often be optimized by using an object with the keys as the switches and the values as the return values.

const dayNumber = new Date().getDay();

// Long-hand
let day;
switch (dayNumber) {
  case 0:
    day = "Sunday";
    break;
  case 1:
    day = "Monday";
    break;
  case 2:
    day = "Tuesday";
    break;
  case 3:
    day = "Wednesday";
    break;
  case 4:
    day = "Thursday";
    break;
  case 5:
    day = "Friday";
    break;
  case 6:
    day = "Saturday";
}

// Short-hand
const days = {
  0: "Sunday",
  1: "Monday",
  2: "Tuesday",
  3: "Wednesday",
  4: "Thursday",
  5: "Friday",
  6: "Saturday",
};
const day = days[dayNumber];

7. Fallback values

The || operator can set a fallback value for a variable.

// Long-hand
let name;
if (user?.name) {
  name = user.name;
} else {
  name = "Anonymous";
}

// Short-hand
const name = user?.name || "Anonymous";

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Comments

[Exo Des]

I think the the fallback values need some correction. Using logical OR || doesn’t give you the value you want if the value is [] or 0. The better solution would be using the nullish coalescence ?? where if only use the fallback values when the defined value is null or undefined.

[Rich Winter]

☝️

[Erian]

☝️

[Oliver Kühn]

☝️

[Emre Birkan Kervan]

☝️

[pogpog]

☝️

[Gabriel Andres]

☝️

[Ben Sinclair]

In point 1, everything's fine, but you make the "long hand" version look longer by adding a redundant if.. else. This would be a better comparison:

// Long-hand
const isVowel = (letter) => {
  return (
    letter === "a" ||
    letter === "e" ||
    letter === "i" ||
    letter === "o" ||
    letter === "u"
  );
};

In point 4 I would recommend against nesting ternaries because you quickly get an unreadable mess of code, especially when the lines contain long strings which wrap in your editor.

[Posandu]

Nice post!

The 5th can be changed as follows

function f1() {
    // ...
}
function f2() {
    // ...
}

conditon ? f1() : f2();

And the 6th can be improved by using Arrays

const dayNumber = new Date().getDay();

const days = [
    "Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday",
];
// Or
const days = `Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday`.split(
    ","
);

const day = days[dateNumber];

[Frank Wisniewski]

    const weekday = new Intl.DateTimeFormat('de-DE',{weekday: 'long'}).format(new Date())

[Rich Winter]

Suggestion is a bit of a "premature optimization" - you just created a string " Sunday" instead of "Sunday"

With something like this, sometimes the longer way is just easier for the next guy to read. Especially when that next guy is you.

[Sam oo Líng]

(condition ? f1 : f2)();

Is a new thing for me, but why'd you suggest

conditon ? f1() : f2();

instead?

[Posandu]

If you need to add different arguments to each function call. You can't do it from the 1st method.

[Sam oo Líng]

ah so that's why..

[Gorisso-manuchi]

hi my friend

[Sam oo Líng]

hello too

[Undefined Dev]

Good job with the article, but I do have some things to say:
For #7, I'd rather go with the nullish coalescing operator(??) than ||...
And for #4, wouldn't it be a good idea to talk about why someone shouldn't use ternary operators too much as well, i.e., nested ternary operators can be a nightmare for readability, and recommending against it would be good for people who are learning about ternary operators.

[Alex]

Nested ternary would never pass my code review. IMO, one-liner is not an optimization if it affects readability.

Even though your #1 example is more general, this specific case can be shortened:

const isVowel = (letter) =>
  'aeiou'.indexOf(letter) > -1

[Nishith Savla]

I resist from using indexOf as you can instead use includes

'aeiou'.includes(letter)

[Roland Taylor]

Some great tips here! Thanks for sharing!

[StefanTheSpider]

I miss the unicorn 🥲

[WebSharp]

thanks for sharing this stuff

[Madza]

Some great tips right here, thanks 👍💯

[Timothy Huang]

Interesting and useful, thanks for sharing.