5 Javascript shorthands you should start using today - part 2

Today is all about arrays in javascript. Some mistakes, some tweaks and some solutions for you today.

1. Switch cases Arrays

In this example our ultimate goal is to return the day's name depending on the dayNumber we get.

Longhand ❌:

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

Shorthand ✅:

const days = [
    "Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday",
];
const day = days[dayNumber];

2. Find in Arrays

Let's remove weekends from a week and try to find it in the array.

Longhand ❌:

const isDay = (day) => {
  if (
    day === "Monday"
    day === "Tuesday"
    day === "Wednesday"
    day === "Thursday"
    day === "Friday"
  ) {
    return true;
  }
  return false;
};

Shorthand ✅:

const days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"];
const isVowel = (day) => days.includes(day);

2 benefits:

• You remove static written if block and replace it with an array, which is more dynamic(you just need to add a new value for check).
• You make your code less crowded and more clear with the shorthand. THe credit goes to .includes().

3. For-of and For-in loops

Here we will talk about traversing thorugh array and an JSON(Object).

For-of

Longhand ❌:

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

• Here we have un-necessary let declaration which takes up some memory of the pc, which is bad if we follow this syntax multiple times.

Shorthand ✅:

for (const element of arr) {
    // ...
}

• Here we have eliminate let declaration.
• We also make the code less noisy and logical.

For-in

Longhand ❌:

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

Shorthand ✅:

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

• Similar benefits to the For-of.

4. Multple values in one line

let num1, num2;

Longhand ❌:

num1 = 10;
num2 = 100;

Shorthand ✅:

[num1, num2] = [10, 100];

5. Swap two variables in one line

let x = 1; let y = 2; Longhand ❌:

let temp = x;
x = y;
y = temp;

Shorthand ✅:

[x, y] = [y, x];

Check the same code here Codesandbox

That was all folks 😎! We will continue with some more interesting shorthands and tricks in the next one.

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