preface

Recently saw some simplified JS code, one feels good, but is in English, also saw some Chinese translation, is a literal translation is too hard and not become their own things, another is behind the author doesn’t have a new update, so I translated into this article according to their own language, in this paper, characteristic with concise give priority to

20 JavaScript Techniques that Will Save Your Time

The body of the

Shorthand skills

When multiple variables are declared at the same time, it can be shortened to a single line

//Longhand
let x;
let y = 20;
 
//Shorthand
let x, y = 20;
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With deconstruction, multiple variables can be assigned simultaneously

//Longhand
let a, b, c;

a = 5;
b = 8;
c = 12;

//Shorthand
let [a, b, c] = [5.8.12];
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Clever ternary operators to simplify if else

//Longhand 
let marks = 26; 
let result; 
if (marks >= 30) {
   result = 'Pass'; 
} else { 
   result = 'Fail'; 
} 

//Shorthand 
let result = marks >= 30 ? 'Pass' : 'Fail';
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Using the | | operator to variable specifies the default values

Essence is the use of the | | operator, the characteristics of the current expression of the results when they are converted to Boolean value of false value as the result of the following expression

//Longhand
let imagePath;

let path = getImagePath();

if(path ! = =null&& path ! = =undefined&& path ! = =' ') {
    imagePath = path;
} else {
    imagePath = 'default.jpg';
}

//Shorthand
let imagePath = getImagePath() || 'default.jpg';
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Simplify if statements with && operators

For example, a function is called only if a condition is true

//Longhand
if (isLoggedin) {
    goToHomepage();
 }

//Shorthand
isLoggedin && goToHomepage();
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Use deconstruction to exchange the values of two variables

let x = 'Hello', y = 55;

//Longhand
const temp = x;
x = y;
y = temp;

//Shorthand
[x, y] = [y, x];
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Apply the arrow function to simplify the function

//Longhand
function add(num1, num2) {
  return num1 + num2;
}

//Shorthand
const add = (num1, num2) = > num1 + num2;
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Note the difference between arrow functions and normal functions

Simplify code with string templates

Use template strings instead of the original string concatenation

//Longhand
console.log('You got a missed call from ' + number + ' at ' + time);

//Shorthand
console.log(`You got a missed call from ${number} at ${time}`);
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Multi-line strings can also be simplified using string templates

//Longhand
console.log('JavaScript, often abbreviated as JS, is a\n' + 
            'programming language that conforms to the \n' + 
            'ECMAScript specification. JavaScript is high-level,\n' + 
            'often just-in-time compiled, and multi-paradigm.'
            );


//Shorthand
console.log(`JavaScript, often abbreviated as JS, is a programming language that conforms to the ECMAScript specification. JavaScript is high-level, often just-in-time compiled, and multi-paradigm.`
            );
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For multi-value matching, you can put all values in an array, shorthand by array methods

//Longhand
if (value === 1 || value === 'one' || value === 2 || value === 'two') {
  // Execute some code
}

// Shorthand 1
if ([1.'one'.2.'two'].indexOf(value) >= 0) {
   // Execute some code
}

// Shorthand 2
if ([1.'one'.2.'two'].includes(value)) { 
    // Execute some code 
}
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Use the concise syntax of ES6 objects

For example, when an attribute name and a variable name are the same, they can be shortened to one

let firstname = 'Amitav';
let lastname = 'Mishra';

//Longhand
let obj = {firstname: firstname, lastname: lastname};

//Shorthand
let obj = {firstname, lastname};
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Use unary operators to simplify string to number conversion

//Longhand
let total = parseInt('453');
let average = parseFloat('42.6');

//Shorthand
let total = +'453';
let average = +'42.6';
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Use the repeat() method to simplify repeating a string

//Longhand
let str = ' ';
for(let i = 0; i < 5; i ++) {
  str += 'Hello ';
}
console.log(str); // Hello Hello Hello Hello Hello

// Shorthand
'Hello '.repeat(5);

// I want to say 100 sorry to you!
'sorry\n'.repeat(100);
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Use double stars instead of math.pow ()

//Longhand
const power = Math.pow(4.3); / / 64

// Shorthand
const power = 4**3; / / 64
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Use the double tilde operator (~~) instead of math.floor ()

//Longhand
const floor = Math.floor(6.8); / / 6

// Shorthand
const floor = ~~6.8; / / 6
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Note that ~~ only applies to numbers less than 2,147,483,647

Ingenious extension operators (…) Simplify the code

Simplified array merge

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]
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A copy of a single layer object

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));

//Shorthand for single level object
let obj = {x: 20.y: 'hello'};
constcloneObj = {... obj};Copy the code

Find the maximum and minimum values in the array

// Shorthand
const arr = [2.8.15.4];
Math.max(... arr);/ / 15
Math.min(... arr);/ / 2
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Use for in and for of to simplify normal for loops

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]);
}
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Simplifies getting a character in a string

let str = 'jscurious.com';

//Longhand
str.charAt(2); // c

//Shorthand
str[2]; // c
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Removing object properties

let obj = {x: 45.y: 72.z: 68.p: 98};

// Longhand
delete obj.x;
delete obj.p;
console.log(obj); // {y: 72, z: 68}

// Shorthand
let{x, p, ... newObj} = obj;console.log(newObj); // {y: 72, z: 68}
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Use arr. Filter (Boolean) to filter out the value of the array member falsey

let arr = [12.null.0.'xyz'.null, -25.NaN.' '.undefined.0.5.false];

//Longhand
let filterArray = arr.filter(function(value) {
    if(value) return value;
});
// filterArray = [12, "xyz", -25, 0.5]

// Shorthand
let filterArray = arr.filter(Boolean);
// filterArray = [12, "xyz", -25, 0.5]
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THE END

The articles (except the code) are organized in my own language and are abridged. If necessary, link to Amitav Mishra’s personal blog
In the body part of the code, Longhand indicates the normal form and Shorthand indicates the type
That’s all for this article. If you have any questions, please leave a comment at 🌹~

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20 Efficient JS shorthand Tips

preface

The body of the

Shorthand skills

When multiple variables are declared at the same time, it can be shortened to a single line

With deconstruction, multiple variables can be assigned simultaneously

Clever ternary operators to simplify if else

Using the | | operator to variable specifies the default values

Simplify if statements with && operators

Use deconstruction to exchange the values of two variables

Apply the arrow function to simplify the function

Simplify code with string templates

Use template strings instead of the original string concatenation

Multi-line strings can also be simplified using string templates

For multi-value matching, you can put all values in an array, shorthand by array methods

Use the concise syntax of ES6 objects

Use unary operators to simplify string to number conversion

Use the repeat() method to simplify repeating a string

Use double stars instead of math.pow ()

Use the double tilde operator (~~) instead of math.floor ()

Ingenious extension operators (…) Simplify the code

Simplified array merge

A copy of a single layer object

Find the maximum and minimum values in the array

Use for in and for of to simplify normal for loops

Simplifies getting a character in a string

Removing object properties

Use arr. Filter (Boolean) to filter out the value of the array member falsey

THE END

20 Efficient JS shorthand Tips

preface

The body of the

Shorthand skills

When multiple variables are declared at the same time, it can be shortened to a single line

With deconstruction, multiple variables can be assigned simultaneously

Clever ternary operators to simplify if else

Using the | | operator to variable specifies the default values

Simplify if statements with && operators

Use deconstruction to exchange the values of two variables

Apply the arrow function to simplify the function

Simplify code with string templates

Use template strings instead of the original string concatenation

Multi-line strings can also be simplified using string templates

For multi-value matching, you can put all values in an array, shorthand by array methods

Use the concise syntax of ES6 objects

Use unary operators to simplify string to number conversion

Use the repeat() method to simplify repeating a string

Use double stars instead of math.pow ()

Use the double tilde operator (~~) instead of math.floor ()

Ingenious extension operators (…) Simplify the code

Simplified array merge

A copy of a single layer object

Find the maximum and minimum values in the array

Use for in and for of to simplify normal for loops

Simplifies getting a character in a string

Removing object properties

Use arr. Filter (Boolean) to filter out the value of the array member falsey

THE END

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