The shorthand techniques of any programming language help you to write more clean and optimized code. Shorthand techniques improve readability of your code and you can achieve your goal with less coding. Let’s discuss some of the shorthand techniques of JavaScript one by one.
1. Declaring variables
//Longhand
let x; let y = 20;
//Shorthand
let x, y = 20;
2. Assigning values to multiple variables
We can assign values to multiple variables in one line with array destructuring.
//Longhand
let a, b, c;
a = 5;
b = 8;
c = 12;
//Shorthand
let [a, b, c] = [5, 8, 12];
3. The Ternary operator
We can save 5 lines of code here with ternary (conditional) operator.
//Longhand
let number = 26;
let isEven;
if(number % 2){
isEven = true;
}else{
isEven = false;
}
//Shorthand
let isEven = number % 2 ? true : false;
4. Assigning default value
We can use OR(||)short circuit evaluation to assign a default value to a variable in case the expected value found empty.
//Longhand
let imagePath;
let path = getImagePath();
if(path !== null && path !== undefined && path !== '') {
imagePath = path;
} else {
imagePath = 'default.jpg';
}
//Shorthand
let imagePath = getImagePath() || 'default.jpg';
5. AND(&&) Short circuit evaluation
If you are calling a function only if a variable is true, then using AND(&&) short circuit you can do it in a single line.
//Longhand
if (isLoggedin) {
goToHomepage();
}
//Shorthand
isLoggedin && goToHomepage();
Here in shorthand technique, if isLoggedin returns true, then only goToHomepage()will execute.
6. Swap two variables
To swap two variables, we often use a third variable. We can swap two variables easily with array destructuring assignment.
let x = 'Hello', y = 55;
//Longhand
const temp = x;
x = y;
y = temp;
//Shorthand
[x, y] = [y, x];
7. Arrow Function
//Longhand
function add(num1, num2) {
return num1 + num2;
}
//Shorthand
const add = (num1, num2) => num1 + num2;
8. Template Literals
We normally use + operator to concatenate string values with variables. With ES6 template literals we can do it in a more simple way.
//Longhand
console.log('You got a missed call from ' + number + ' at ' + time);
//Shorthand
console.log(`You got a missed call from ${number} at ${time}`);
9. Destructuring Assignment Shorthand
If you are working with any popular web framework, there are high chances you will be using arrays or data in the form of object literals to pass information between components and APIs. Once the data object reaches a component, you’ll need to unpack it.
//Longhand
const observable = require('mobx/observable');
const action = require('mobx/action');
const runInAction = require('mobx/runInAction');
const store = this.props.store;
const form = this.props.form;
const loading = this.props.loading;
const errors = this.props.errors;
const entity = this.props.entity;
// Shorthand
import { observable, action, runInAction } from 'mobx';
const { store, form, loading, errors, entity } = this.props;
You can even assign your own variable names:
const { store, form, loading, errors, entity:contact } = this.props;
10. Multiple condition checking
For multiple value matching, we can put all values in array and use indexOf() method.
//Longhand
if (value === 1 || value === 'one' || value === 2 || value === 'two') {
// Execute some code
}
// Shorthand
if ([1, 'one', 2, 'two'].indexOf(value) >= 0) {
// Execute some code
}
11. Object Property Assignment
If the variable name and object key name is same then we can just mention variable name in object literals instead of both key and value. JavaScript will automatically set the key same as variable name and assign the value as variable value.
let firstname = 'Amitav';
let lastname = 'Mishra';
//Longhand
let obj = {firstname: firstname, lastname: lastname};
//Shorthand
let obj = {firstname, lastname};
12. String into a Number
There are built in methods like parseInt and parseFloat available to convert a string to number. We can also do this by simply providing a unary operator (+) in front of string value.
//Longhand
let total = parseInt('453');
let average = parseFloat('42.6');
//Shorthand
let total = +'453';
let average = +'42.6';
13. Repeat a string for multiple times
To repeat a string for a specified number of time you can use a for loop. But using the repeat() method we can do it in a single line.
//Longhand
let str = '';
for(let i = 0; i < 5; i ++) {
str += 'Hello ';
}
console.log(str); // Hello Hello Hello Hello Hello
// Shorthand
'Hello '.repeat(5);
Tip: Want to apologize to someone by sending 100 times “sorry”? Try it with repeat() method. If you want to repeat each string in a new line, then add \n to the string.
'sorry\n'.repeat(100);
14. Exponent Power
We can use Math.pow() method to find the power of a number. There is a shorter syntax to do it with double asterik (**).
//Longhand
const power = Math.pow(4, 3); // 64
// Shorthand
const power = 4**3; // 64
15. Double NOT bitwise operator (~~)
The double NOT bitwise operator is a substitute for Math.floor() method.
//Longhand
const floor = Math.floor(6.8); // 6
// Shorthand
const floor = ~~6.8; // 6
16. Find max and min number in array
We can use for loop to loop through each value of array and find the max or min value. We can also use the Array.reduce() method to find the max and min number in array.But using spread operator we can do it in a single line.
// Shorthand
const arr = [2, 8, 15, 4];
Math.max(...arr); // 15
Math.min(...arr); // 2
17. For loop
To loop through an array we normally use the traditional for loop. We can make use of the for...of loop to iterate through arrays. To access the index of each value we can use for...in loop.
let arr = [10, 20, 30, 40];
//Longhand
for (let i = 0; i < arr.length; i++) {
console.log(arr[i]);
}
//Shorthand
//for of loop
for (const val of arr) {
console.log(val);
}
//for in loop
for (const index in arr) {
console.log(arr[index]);
}
We can also loop through object properties using for...in loop.
let obj = {x: 20, y: 50};
for (const key in obj) {
console.log(obj[key]);
}
18. Merging of arrays
let arr1 = [20, 30];
//Longhand
let arr2 = arr1.concat([60, 80]);
// [20, 30, 60, 80]
//Shorthand
let arr2 = [...arr1, 60, 80];
// [20, 30, 60, 80]
19. Deep cloning of multi-level object
To deep clone a multi-level object, we can iterate through each property and check if the current property contains an object. If yes, then do a recursive call to the same function by passing the current property value (i.e. the nested object).We can also do it by using JSON.stringify() and JSON.parse() in a single line.
let obj = {x: 20, y: {z: 30}};
//Longhand
const makeDeepClone = (obj) => {
let newObject = {};
Object.keys(obj).map(key => {
if(typeof obj[key] === 'object'){
newObject[key] = makeDeepClone(obj[key]);
} else {
newObject[key] = obj[key];
}
});
return newObject;
}
const cloneObj = makeDeepClone(obj);
//Shorthand
const cloneObj = JSON.parse(JSON.stringify(obj));
20. Get character from string
let str = 'jscurious.com';
//Longhand
str.charAt(2); // c
//Shorthand
str[2]; // c
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