What I want to share today is 10 It's a great JavaScript Shorthand method , Can speed up development , Let your development work get twice the result with half the effort .
Let's get started ！
1. Merge array
Common writing ：
We usually use Array Medium concat() Method to merge two arrays . use concat() Method to merge two or more arrays , The existing array... Will not be changed , Instead, it returns a new array . Look at a simple example ：
let apples = ['', ''];
let fruits = ['', '', ''].concat(apples);
console.log( fruits );
//=> ["", "", "", "", ""]
Shorthand method ：
We can do that by using ES6 Extension operator (...) To reduce code , As shown below ：
let apples = ['', ''];
let fruits = ['', '', '', ...apples]; // <-- here
console.log( fruits );
//=> ["", "", "", "", ""]
The output is the same as the normal writing method .
2. Merge array （ At the beginning ）
Common writing ：
Suppose we want to apples All items in the array are added to Fruits The beginning of the array , Instead of putting it at the end as in the previous example . We can use Array.prototype.unshift() To do that ：
let apples = ['', ''];
let fruits = ['🥭', '', ''];
// Add all items from apples onto fruits at start
Array.prototype.unshift.apply(fruits, apples)
console.log( fruits );
//=> ["", "", "🥭", "", ""]
Now the red and green apples will merge at the beginning, not at the end .
Shorthand method ：
We can still use ES6 Extension operator (...) Shorten this long code , As shown below ：
let apples = ['', ''];
let fruits = [...apples, '🥭', '', '']; // <-- here
console.log( fruits );
//=> ["", "", "🥭", "", ""]
3. Clone array
Common writing ：
We can use Array Medium slice() Method to easily clone an array , As shown below ：
let fruits = ['', '', '', ''];
let cloneFruits = fruits.slice();
console.log( cloneFruits );
//=> ["", "", "", ""]
Shorthand method ：
We can use ES6 Extension operator (...) Clone an array like this ：
let fruits = ['', '', '', ''];
let cloneFruits = [...fruits]; // <-- here
console.log( cloneFruits );
//=> ["", "", "", ""]
4. Deconstruct assignment
Common writing ：
When working with arrays , We sometimes need to put arrays “ Unpack ” Into a pile of variables , As shown below ：
let apples = ['', ''];
let redApple = apples[0];
let greenApple = apples[1];
console.log( redApple ); //=>
console.log( greenApple ); //=>
Shorthand method ：
We can achieve the same result in one line of code by deconstructing the assignment ：
let apples = ['', ''];
let [redApple, greenApple] = apples; // <-- here
console.log( redApple ); //=>
console.log( greenApple ); //=>
5. Template literal
Common writing ：
Usually , When we have to add an expression to a string , We'll do that ：
// Display name in between two strings
let name = 'Palash';
console.log('Hello, ' + name + '!');
//=> Hello, Palash!
// Add & Subtract two numbers
let num1 = 20;
let num2 = 10;
console.log('Sum = ' + (num1 + num2) + ' and Subtract = ' + (num1 - num2));
//=> Sum = 30 and Subtract = 10
Shorthand method ：
Through template literal , We can use backquotes (), So we can wrap the expression in ${...}\` in , Then embedded into the string , As shown below ：
// Display name in between two strings
let name = 'Palash';
console.log(`Hello, ${name}!`); // <-- No need to use + var + anymore
//=> Hello, Palash!
// Add two numbers
let num1 = 20;
let num2 = 10;
console.log(`Sum = ${num1 + num2} and Subtract = ${num1 - num2}`);
//=> Sum = 30 and Subtract = 10
6. For loop
Common writing ：
We can use for Loop loops through an array like this ：
let fruits = ['', '', '', ''];
// Loop through each fruit
for (let index = 0; index < fruits.length; index++) {
console.log( fruits[index] ); // <-- get the fruit at current index
}
//=>
//=>
//=>
//=>
Shorthand method ：
We can use for...of Statement to achieve the same result , And much less code , As shown below ：
let fruits = ['', '', '', ''];
// Using for...of statement
for (let fruit of fruits) {
console.log( fruit );
}
//=>
//=>
//=>
//=>
7. Arrow function
Common writing ：
You're going through groups , We can also use Array Medium forEach() Method . But you need to write a lot of code , Although more than the most common for Fewer cycles , But still more than for...of More sentences ：
let fruits = ['', '', '', ''];
// Using forEach method
fruits.forEach(function(fruit){
console.log( fruit );
});
//=>
//=>
//=>
//=>
Shorthand method ：
But using the arrow function expression , Allows us to write complete loop code in one line , As shown below ：
let fruits = ['', '', '', ''];
fruits.forEach(fruit => console.log( fruit )); // <-- Magic
//=>
//=>
//=>
//=>
Most of the time I use functions with arrows forEach loop , Here I put for...of Statement and forEach Cycles are shown , It is convenient for everyone to use the code according to their preferences .
8. Find objects in an array
Common writing ：
To find an object from an object array through one of its properties , We usually use for loop ：
let inventory = [
{name: 'Bananas', quantity: 5},
{name: 'Apples', quantity: 10},
{name: 'Grapes', quantity: 2}
];
// Get the object with the name `Apples` inside the array
function getApples(arr, value) {
for (let index = 0; index < arr.length; index++) {
// Check the value of this object property `name` is same as 'Apples'
if (arr[index].name === 'Apples') { //=>
// A match was found, return this object
return arr[index];
}
}
}
let result = getApples(inventory);
console.log( result )
//=> { name: "Apples", quantity: 10 }
Shorthand method ：
wow ！ We have written so much code to implement this logic . But use Array Medium find() Methods and arrow functions =>, Allow us to do things like this ：
// Get the object with the name `Apples` inside the array
function getApples(arr, value) {
return arr.find(obj => obj.name === 'Apples'); // <-- here
}
let result = getApples(inventory);
console.log( result )
//=> { name: "Apples", quantity: 10 }
9. Convert string to integer
Common writing ：
parseInt() The function parses a string and returns an integer ：
let num = parseInt("10")
console.log( num ) //=> 10
console.log( typeof num ) //=> "number"
Shorthand method ：
We can add... Before the string + Prefix to achieve the same result , As shown below ：
let num = +"10";
console.log( num ) //=> 10
console.log( typeof num ) //=> "number"
console.log( +"10" === 10 ) //=> true
10. Short circuit evaluation
Common writing ：
If we have to set a value according to another value, it is not falsy value , You usually use if-else sentence , Just like this. ：
function getUserRole(role) {
let userRole;
// If role is not falsy value
// set `userRole` as passed `role` value
if (role) {
userRole = role;
} else {
// else set the `userRole` as USER
userRole = 'USER';
}
return userRole;
}
console.log( getUserRole() ) //=> "USER"
console.log( getUserRole('ADMIN') ) //=> "ADMIN"
Shorthand method ：
But using short-circuit evaluation (||), We can do this in one line of code , As shown below ：
function getUserRole(role) {
return role || 'USER'; // <-- here
}
console.log( getUserRole() ) //=> "USER"
console.log( getUserRole('ADMIN') ) //=> "ADMIN"
Basically ,expression1 || expression2 Assessed as really expression . therefore , This means that if the first part is true , You don't have to worry about evaluating the rest of the expression .
Add a few
Arrow function
If you don't need to this Context , The code can also be shorter when using the arrow function ：
let fruits = ['', '', '', ''];
fruits.forEach(console.log);
Find objects in an array
You can use object deconstruction and arrow functions to streamline your code ：
// Get the object with the name `Apples` inside the array
const getApples = array => array.find(({ name }) => name === "Apples");
let result = getApples(inventory);
console.log(result);
//=> { name: "Apples", quantity: 10 }
Short circuit evaluation alternatives
const getUserRole1 = (role = "USER") => role;
const getUserRole2 = role => role ?? "USER";
const getUserRole3 = role => role ? role : "USER";
Coding habits
Finally, I want to talk about coding habits . Code specifications abound , But few people strictly abide by . The reason is , Most of them are before the code specification , Has its own set of code habits , It's hard to change your habits in a short time . Good coding habits can lay a good foundation for subsequent growth . below , List a few benefits of developing a specification , Let us understand the importance of code specification ：
- Standardized code can promote teamwork .
- Standardized code can reduce Bug Handle .
- Standardized code can reduce maintenance costs .
- Standardized code helps code review .
- Get into the habit of code normalization , It's good for the growth of programmers themselves .
What I'm looking at myself is 《 Alibaba front end development specification 》, The code specification inside is very complete , And basically universal , It's very useful after reading . The space for , The following is a screenshot showing the directory and some contents , complete PDF Click here You can download for free .
Catalog 
One 、 Coding standards
Two 、Vue Project specifications
That is 《 Alibaba front end development specification 》, A little friend in need Click here You can download for free .
Last , I'd like to end with a passage ：
Code is our enemy , Because many of our programmers write a lot of shit code . If we can't get rid of , Then it's best to do your best to keep the code simple .
If you like to write code —— Really? , I really like writing code —— The less code you write , The deeper your love .
