把日期类型转成字符串类型
dateFormat(time) {
if (time == null || time == "" || time == " ") {
return "";
}
time = new Date(time);
let year = time.getFullYear();
let month = (time.getMonth() + 1) >= 10 ? (time.getMonth() + 1) : 0 + "" + (time.getMonth() + 1);
let day = time.getDate() >= 10 ? time.getDate() : 0 + "" + time.getDate();
time = year + "-" + month + "-" + day;
return time; }
求 数组的最小值
Math.trunc(Math.min.apply(null, minnum));
求 数组的最大值
var minnum = [ 2,7,8,4,6,5]
Math.trunc(Math.max.apply(null, minnum));
求 平均值
function average(nums) {
return (nums.reduce((a, b) => Number(a) + Number(b)) / nums.length).toFixed(2);
}
average(minnum);
生成随机UID
const genUid = ()=> {
var length = 20
var soupLength = genUid.soup_.length
var id = []
for (var i = 0; i < length; i++) {
id[i] = genUid.soup_.charAt(Math.random() * soupLength)
}
return id.join('')
}
genUid.soup_ = '!#$()*+,-./:;=@[]^_`{|}~ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'；
genUid() // ;l`yCPc9A8IuK}?N6,%}
无loop生成指定长度的数组
const List = len=> [...new Array(len).keys()]
const list = List(10) // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
RGB色值生成16进制色值
const rgb2Hex = (r, g, b) => {
r = Math.max(Math.min(Number(r), 100), 0) * 2.55
g = Math.max(Math.min(Number(g), 100), 0) * 2.55
b = Math.max(Math.min(Number(b), 100), 0) * 2.55
r = ('0' + (Math.round(r) || 0).toString(16)).slice(-2)
g = ('0' + (Math.round(g) || 0).toString(16)).slice(-2)
b = ('0' + (Math.round(b) || 0).toString(16)).slice(-2)
return '#' + r + g + b
}
rgb2Hex(100, 50, 0) // "#ff7f00"
颜色混合
const colourBlend = (c1, c2, ratio) => {
ratio = Math.max(Math.min(Number(ratio), 1), 0)
let r1 = parseInt(c1.substring(1, 3), 16)
let g1 = parseInt(c1.substring(3, 5), 16)
let b1 = parseInt(c1.substring(5, 7), 16)
let r2 = parseInt(c2.substring(1, 3), 16)
let g2 = parseInt(c2.substring(3, 5), 16)
let b2 = parseInt(c2.substring(5, 7), 16)
let r = Math.round(r1 * (1 - ratio) + r2 * ratio)
let g = Math.round(g1 * (1 - ratio) + g2 * ratio)
let b = Math.round(b1 * (1 - ratio) + b2 * ratio)
r = ('0' + (r || 0).toString(16)).slice(-2)
g = ('0' + (g || 0).toString(16)).slice(-2)
b = ('0' + (b || 0).toString(16)).slice(-2)
return '#' + r + g + b
}
colourBlend('#ff0000', '#3333ff', 0.5) // "#991a80"
判断是否为质数
const mathIsPrime = n=> {
if (n === 2 || n === 3) {
return true
}
if (isNaN(n) || n <= 1 || n % 1 != 0 || n % 2 == 0 || n % 3 == 0) {
return false;
}
for (let x = 6; x <= Math.sqrt(n) + 1; x += 6) {
if (n % (x - 1) == 0 || n % (x + 1) == 0) {
return false
}
}
return true
}
mathIsPrime(0) // true
遍历类数组对象
const elements = document.querySelectorAll(selector);
[].prototype.forEach.call(elements, (el, idx, list) => {
console.log(el) // 元素节点
})
优化多层判断条件
const getScore = score=> {
const scoreData = new Array(101).fill(0)
.map((data, idx) => ([idx, () => (idx < 60 ? '不及格' : '及格')]))
const scoreMap = new Map(scoreData)
return (scoreMap.get(score)
? scoreMap.get(score)()
: '未知分数')
}
getScore(30) // 不及格
时间格式化
const dateFormatter = (formatter, date) => {
date = (date ? new Date(date) : new Date)
const Y = date.getFullYear() + '',
M = date.getMonth() + 1,
D = date.getDate(),
H = date.getHours(),
m = date.getMinutes(),
s = date.getSeconds()
return formatter.replace(/YYYY|yyyy/g, Y)
.replace(/YY|yy/g, Y.substr(2, 2))
.replace(/MM/g, (M < 10 ? '0' : '') + M)
.replace(/DD/g, (D < 10 ? '0' : '') + D)
.replace(/HH|hh/g, (H < 10 ? '0' : '') + H)
.replace(/mm/g, (m < 10 ? '0' : '') + m)
.replace(/ss/g, (s < 10 ? '0' : '') + s)
}
dateFormatter('YYYY-MM-DD HH:mm', '1995/02/15 13:55') // 1995-02-15 13:55
