终极JavaScript秘籍,建议收藏食用

终极JavaScript秘籍,建议收藏食用

首页休闲益智Numberzilla安卓版更新时间:2024-08-01

备忘单是我们开发人员始终需要的参考。因此,这里我编译了许多JavaScript参考代码。查看分类并找到它。这篇文章对学习者和开发人员都有帮助。


JavaScript Number方法备忘单

function expo(x, f) { return Number.parseFloat(x).toExponential(f); } console.log(expo(123456, 2)); // -> 1.23e 5

function financial(x) { return Number.parseFloat(x).toFixed(2); } console.log(financial(123.456)); // -> 123.46

function precise(x) { return Number.parseFloat(x).toPrecision(4); } console.log(precise(123.456)); // -> 123.5

function hexColour(c) { if (c < 256) { return Math.abs(c).toString(16); } return 0; } console.log(hexColour(233)); // -> e9

const numObj = new Number(42); console.log(typeof numObj); // -> object const num = numObj.valueOf(); console.log(num); // -> 42 console.log(typeof num); // -> number


JavaScript循环备忘单

for (var i = 0; < 10; i ) { console.log(i ": " i * 3 "<br />"); } // -> 0: 0<br /> // -> 1: 3<br /> // -> ... let a = [1, 2, 3]; var sum = 0; for (var i - 0; i <a.length; i ) { sum = a[i]; } // pasing an array console.log(sum); // -> 6

var i = 1; // initialize while (i < 100) { // enters the cycle if statement is true i *= 2; // increment to avoid infinte loop console.log(i ", "); // output } // 2, // 4, // ... // 128,

var i = 1; // initialize while (i < 100) { // enters the cycle asleast once i *= 2; // increment to avoid infinte loop console.log(i ", "); // output } while (1 < 100); // repeats cycle if statement is true at the end // 2, // 4, // ... // 128,

for (var i = 0; i < 10; i ) { if (i == 5 ) { break; } // stops and exits the cycle console.log(i ", "); // Lat output number is 4 } // -> 0, // -> 1, // ... // -> 4,

for (var i = 0; i < 10; i ) { if (i == 5 ) { continue; } // skips the rest of the cycle console.log(i ", "); // skips 5 } // -> 0, // -> 1, // ... // -> 9,


JavaScript字符串方法备忘单

const sentence = "Jeff bezos is now the second richest."; const index = 4; console.log(`The character at index ${index} is ${sentence.charAt(index)}`); // The character at index 4 is f

const str1 = "Hello"; cosnt str2 = "World"; console.log(str1.concat(" ", str2)); // -> Hello World console.log(str2.concat(", ", str1)); // -> World, Hello

const p = "Talk is cheap. Show me the work. - Someone"; console.log(p.replace("work", "code")); // -> Talk is cheap. Show me the code. - Someone

const paragraph = "The quick brown fox jumps over the lazy dog."; // any character that is not a word character or whitespace const regex = /[^\w\s]/g; console.log(paragraph.search(regex)); // -> 43

const str = "The quick brown fox jumps over the lazy dog."; consolelog(str.slice(31)); // -> the lazy dog console.log(str.slice(4, 19)); // -> quick brown fox

const greeting = " Hello world! "; console.log(greeting); // -> Hello world! console.log(greeting.trim()); // -> Hello world!

const str = "Mozilla"; console.log(str.substr(1, 2)); // -> oz console.log(stre.substr(2)); // -> zilla

const sentence = "Elon became the richest last night."; console.log(sentence.toLowerCase()); // -> elon became the richest last night.


JavaScript数组方法指导表

let array1 = ["a", "b", "c"]; let array2 = ["d", "e", "f"]; let array3 = array1.concat(array2); console.log(array3); // -> Array(6) ["a", "b", "c", "d", "e", "f" ]

let beasts = ["ant", "bison", "camel", "duck", "bison"]; console.log(beasts.indexOf("bison")); // -> 1 // start from index 2 console.log(beasts.indexOf("bison", 2)); // -> 4

let elements = ["Fire", "Air", "Water"]; console.log(elements.join()); // -> Fire,Air,Water console.log(elements.join(" ")); // -> Fire Air Water

let plants = ["broccoli", "cauliflower", "cabbage", "kale", "tomato"]; console.log(plants.pop()); // -> tomato console.log(plants); // -> Array(4) ["brocxoli", "cauliflower", "cabbage", "kale"]

let array1 = ["one", "two", "three"]; console.log("array1:", array1); // -> array1: Array(3) [ "one", "two", "three" ] let reversed = array1.reverse(); console.log("reversed", reversed); // -> reversed: Array(3) [ "three", "two", "one" ]

let array1 = [1, 2, 3]; let firstElement = array1.shift(); console.log(array1); // -> Array [ 2, 3 ]

let months = ["March", "Jan", "Feb", "Dec"]; months.sort(); console.log(months); // -> Array(4) [ "Dec", "Feb", "Jan", "March" ]

const array1 = [1, 2, "a", "1a"]; console.log(array1.toString()); // -> 1,2,a,1a


JavaScript数据类型备忘单

var age = 18; // Number var name = "Rahul"; // string var name = {first:"Rahul", last:"Singh"}; // object var truth = false; // boolean var sheets = ["HTML", "CSS", "JS"]; // array var a; typeof a; // undefined var a = null; // value null


JavaScript运算符备忘单

a = b c - d; // addition, substraction a = b * (c / d); // multiplication, division x = 100 % 48; // modulo. 100 / 48 remainder = 4 a ; b--; // postfix increment and decrement


变量备忘单

var a; // variable var b = "init"; // string var c = "Hi" "" "Rahul"; // "Hi Rahul" var d = 1 2 "3"; // "33" var e = [2,3,5,8]; // array var f = false; // boolean var g = /()/; // RegEx var h = function(){}; // function object const PI = 3.14; // constant var a = 1, b = 2, c = a b; // one line let z = 'zzz'; // block scope local variable


获取日期方法提示表

const moonLanding = new Date("January 08, 69 00:20:10"); console.log(moonLanding.getFullYear()); // -> 1969

const moonLanding = new Date("January 08, 69 00:20:10"); console.log(moonLanding.getMonth()); // (January gives 0) // -> 6

const birthday = new Date("June 16, 2004 23:14:00"); const date1 = birthday.getDate(); console.log(date1); // -> 19

const birthday = new Date("June 16, 04 4:20"); console.log(birthday.getHours()); // -> 4

const birthday = new Date("June 16, 04 04:10"); console.log(birthday.getMinutes()); // -> 20

const moonLanding = newDate("June 16, 69 00:23:11"); console.log(moonLanding.getSeconds()); // -> 18

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