21个面向Web开发人员的JavaScript技巧汇总
作为程序员，编写代码也需要大量的技巧。好的代码可以让人耳目一新、通俗易懂、舒适自然，同时又充满成就感。
因此，整理了一些经常使用的JavaScript开发技巧，希望能让大家写出耳目一新、通俗易懂、舒适自然的代码。
字符串技巧
1、比较时间
const time1 = "2022-03-02 09:00:00";
const time2 = "2022-03-02 09:00:01";
const overtime = time1 < time2;
// overtime => true
2、格式化money
const ThousandNum = num => num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
const money = ThousandNum(1000000);
// money => '1,000,000'
3、生成随机ID
const RandomId = len => Math.random().toString(36).substr(3, len);
const id = RandomId(10);
// id => "xdeguewg1f"
4、生成随机 HEX 颜色值
const RandomColor = () => "#" + Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0");
const color = RandomColor();
// color => "#2cbf89"
5、Generate star ratings
const StartScore = rate => "★★★★★☆☆☆☆☆".slice(5 - rate, 10 - rate);
const start = StartScore(3);
// start => '★★★☆☆'
6、网址查询参数
const params = new URLSearchParams(location.search.replace(/\?/ig, "")); // location.search = "?name=test&sex=man"
params.has("test"); // true
params.get("sex"); // "man"
数字技能
7、Arrangement
用 Math.floor() 代替正数，用 Math.ceil() 代替负数
const num1 = ~~ 1.19;
const num2 = 2.29 | 0;
const num3 = 3.09 >> 0;
// num1 num2 num3 => 1 2 3
8、零填充
const FillZero = (num, len) => num.toString().padStart(len, "0");
const num = FillZero(1234, 5);
// num => "01234"
9、转数
仅对 null、“”、false、数字字符串有效
const num1 = +null;
const num2 = +"";
const num3 = +false;
const num4 = +"169";
// num1 num2 num3 num4 => 0 0 0 169
10、时间戳
const timestamp = +new Date("2022-03-22");
// timestamp => 1647907200000
11、精确小数
const RoundNum = (num, decimal) => Math.round(num * 10 ** decimal) / 10 ** decimal;
const num = RoundNum(1.2345, 2);
// num => 1.23
12、平价
const OddEven = num => !!(num & 1) ? "odd" : "even";
const num = OddEven(2);
// num => "even"
13、取最小值最大值
const arr = [0, 1, 2, 3];
const min = Math.min(...arr);
const max = Math.max(...arr);
// min max => 0 3
14、生成范围随机数
const RandomNum = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;
const num = RandomNum(1, 10); // 5
布尔技能
布尔技能
15、短路运算符
const a = d && 1; // Fake operation, judge from left to right, return a false value when encountering a false value, and no longer execute it later, otherwise return the last true value
const b = d || 1; // Take the true operation, judge from left to right, return the true value when encountering the true value, and do not execute it later, otherwise return the last false value
const c = !d; // Returns false if a single expression converts to true, otherwise returns true
16、确定数据类型
可确定的类型：undefined、null、string、number、boolean、array、object、symbol、date、regexp、function、asyncfunction、arguments、set、map、weakset、weakmap
function DataType(tgt, type) {
const dataType = Object.prototype.toString.call(tgt).replace(/\[object (\w+)\]/, "$1").toLowerCase();
return type ? dataType === type : dataType;
}
DataType("test"); // "string"
DataType(20220314); // "number"
DataType(true); // "boolean"
DataType([], "array"); // true
DataType({}, "array"); // false
17、检查数组是否为空
const arr = [];
const flag = Array.isArray(arr) && !arr.length;
// flag => true
18、满足条件时执行
const flagA = true; // Condition A
const flagB = false; // Condition B
(flagA || flagB) && Func(); // Execute when A or B is satisfied
(flagA || !flagB) && Func(); // Execute when A is satisfied or B is not satisfied
flagA && flagB && Func(); // Execute when both A and B are satisfied
flagA && !flagB && Func(); // Execute when A is satisfied and B is not satisfied
19、如果非假则执行
const flag = false; // undefined、null、""、0、false、NaN
!flag && Func();
20、数组不为空时执行
const arr = [0, 1, 2];
arr.length && Func();
21、对象不为空时执行
const obj = { a: 0, b: 1, c: 2 };
Object.keys(obj).length && Func();
- End -
*陆荣涛前端学习交流Q群858752519
加群备注：CSDN推荐
