Learn these 20+ JavaScript one-line codes, you can make your code more irritating

JavaScript continues to grow and develop,
Because it is one of the easiest languages to learn, it opens the door on the market to become technical geeks. (Question mark face?)

Indeed, JavaScript can do a lot of great things! There is still a lot to learn.

Moreover, whether you are new to JavaScript or more professional developers, learning new knowledge is always a good thing.

This article has compiled some very useful single lines of code (20+), these single lines of code can help you improve your work efficiency and can help debug your code.

What is a single line of code?

Single line of code is a code practice in which we only use one line of code to perform certain functions.

01-Get Boolean values randomly

This function will use the Math.random() method to return a boolean value (true or false).
Math.random creates a random number between 0 and 1, and then we check whether it is greater than or less than 0.5.
This means there is a 50/50 chance of getting right or wrong.


const getRandomBoolean = () => Math.random() >= 0.5;

console.log(getRandomBoolean());
// a 50/50 chance of returning true or false

02-Check if the date is a weekend

With this function, you will be able to check whether the provided date is a weekday or a weekend.


const isWeekend = (date) => [0, 6].indexOf(date.getDay()) !== -1;

console.log(isWeekend(new Date(2021, 4, 14)));
// false (Friday)
console.log(isWeekend(new Date(2021, 4, 15)));
// true (Saturday)

03-Check if the number is even or odd

Simple utility function to check whether the number is even or odd.


const isEven = (num) => num % 2 === 0;

console.log(isEven(5));
// false
console.log(isEven(4));
// true

04-Get the unique value in the array (array deduplication)

A very simple way to remove all duplicate values from the array. This function converts the array to a Set, and then returns the array.


const uniqueArr = (arr) => [...new Set(arr)];

console.log(uniqueArr([1, 2, 3, 1, 2, 3, 4, 5]));
// [1, 2, 3, 4, 5]

05-Check if the variable is an array

A clean and easy way to check whether a variable is an array.

Of course, there can be other ways too😉


const isArray = (arr) => Array.isArray(arr);

console.log(isArray([1, 2, 3]));
// true
console.log(isArray({ name: 'Ovi' }));
// false
console.log(isArray('Hello World'));
// false

06-Generate a random number between two numbers

This will take two numbers as parameters, and a random number will be generated between these two numbers!

const random = (min, max) => Math.floor(Math.random() * (max - min + 1) + min);

console.log(random(1, 50));
// could be anything from 1 - 50

07-Generate a random string (unique ID?)

Maybe you need temporary unique ID, this is a trick, you can use it to generate random strings on the go.


const randomString = () => Math.random().toString(36).slice(2);

console.log(randomString());
// could be anything!!!

08-Scroll to the top of the page

The window.scrollTo（） method X and Y coordinates to.
If you set them to zero and zero, we will scroll to the top of the page.

const scrollToTop = () => window.scrollTo(0, 0);

scrollToTop();

09- Toggle Boolean

Switching Boolean values is one of the very basic programming problems and can be solved in many different ways.
Instead of using the if statement to determine which value to set the Boolean value to, you can use the function to use! Flip the current value. non-operator.


// bool is stored somewhere in the upperscope
const toggleBool = () => (bool = !bool);
//or
const toggleBool = b => !b;

10- Exchange two variables

The following code is one of the simpler ways to exchange two variables with only one line of code without using the third variable.


[foo, bar] = [bar, foo];

11- Calculate the number of days between two dates

To calculate the number of days between two dates,
We first find the absolute value between the two dates, then divide it by 86400000 (equal to the number of milliseconds in a day), and finally round the result and return it.


const daysDiff = (date, date2) => Math.ceil(Math.abs(date - date2) / 86400000);

console.log(daysDiff(new Date('2021-05-10'), new Date('2021-11-25')));
// 199

12- Copy text to clipboard

PS: You may need to add a check to see if navigator.clipboard.writeText


const copyTextToClipboard = async (text) => {
  await navigator.clipboard.writeText(text);
};

13- Different ways to merge multiple arrays

There are two ways to merge arrays. One of them is to use the concat method. The other uses the spread operator ( … ).

PS: We can also use the "settings" object to copy anything from the final array.


// Merge but don't remove the duplications
const merge = (a, b) => a.concat(b);
// Or
const merge = (a, b) => [...a, ...b];

// Merge and remove the duplications
const merge = [...new Set(a.concat(b))];
// Or
const merge = [...new Set([...a, ...b])];

14- Get the actual type of javascript language

People sometimes use libraries to find the actual type of something in JavaScript, this little trick can save you time (and code size).


const trueTypeOf = (obj) => {
  return Object.prototype.toString.call(obj).slice(8, -1).toLowerCase();
};

console.log(trueTypeOf(''));
// string
console.log(trueTypeOf(0));
// number
console.log(trueTypeOf());
// undefined
console.log(trueTypeOf(null));
// null
console.log(trueTypeOf({}));
// object
console.log(trueTypeOf([]));
// array
console.log(trueTypeOf(0));
// number
console.log(trueTypeOf(() => {}));
// function

15- Truncate the string at the end

The string needs to be truncated from the beginning, this is not a problem!


const truncateString = (string, length) => {
  return string.length < length ? string : `${string.slice(0, length - 3)}...`;
};

console.log(
  truncateString('Hi, I should be truncated because I am too loooong!', 36),
);
// Hi, I should be truncated because...

16-Truncate the string from the middle

How about truncating the string from the middle?

This function takes a string as the first parameter, and then the size of the string we need as the second parameter, and then how many characters are needed to start and end from the 3rd and 4th parameters


const truncateStringMiddle = (string, length, start, end) => {
  return `${string.slice(0, start)}...${string.slice(string.length - end)}`;
};

console.log(
  truncateStringMiddle(
    'A long story goes here but then eventually ends!', // string
    25, // 需要的字符串大小
    13, // 从原始字符串第几位开始截取
    17, // 从原始字符串第几位停止截取
  ),
);
// A long story ... eventually ends!

17-Uppercase string

Well, unfortunately, JavaScript does not have a built-in function to capitalize strings, but this workaround can be implemented.


const capitalize = (str) => str.charAt(0).toUpperCase() + str.slice(1);

console.log(capitalize('hello world'));

// Hello world

18- Check if the current tab is in view/focus

true or false depending on whether the tab is in view/focus state


const isTabInView = () => !document.hidden;  // Not hidden

isTabInView();

// true/false

19- Check if the user is on an Apple device

If the user is using the Apple device, return true


const isAppleDevice = () => /Mac|iPod|iPhone|iPad/.test(navigator.platform);

console.log(isAppleDevice);
// true/false

20-Ternary Operator

This is a good code protection program when you only want to write the if..else


// Longhand
const age = 18;
let greetings;

if (age < 18) {
  greetings = 'You are not old enough';
} else {
  greetings = 'You are young!';
}

// Shorthand
const greetings = age < 18 ? 'You are not old enough' : 'You are young!';

21- Short-circuit assessment shorthand

When assigning a variable value to another variable, you may want to make sure that the source variable is not null, undefined, or empty.
You can write long if statements with multiple conditions, or you can use short-circuit evaluation.


// Longhand
if (name !== null || name !== undefined || name !== '') {
  let fullName = name;
}

// Shorthand
const fullName = name || 'buddy';

Hope it helps you!