前端 UUID生成

export const generateUUID = () => {
	let timestamp = new Date().getTime()
	let performanceNow = (typeof performance !== 'undefined' && performance.now && performance.now() * 1000) || 0
	return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
		let random = Math.random() * 16
		if (timestamp > 0) {
			random = (timestamp + random) % 16 | 0
			timestamp = Math.floor(timestamp / 16)
		} else {
			random = (performanceNow + random) % 16 | 0
			performanceNow = Math.floor(performanceNow / 16)
		}
		return (c === 'x' ? random : (random & 0x3) | 0x8).toString(16)
	})
}

输了格式

UUID的长度

function guid(len = 32, firstU = true, radix = null) {
	const chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('')
	const uuid = []
	radix = radix || chars.length

	if (len) {
		// 如果指定uuid长度,只是取随机的字符,0|x为位运算,能去掉x的小数位,返回整数位
		for (let i = 0; i < len; i++) uuid[i] = chars[0 | Math.random() * radix]
	} else {
		let r
		// rfc4122标准要求返回的uuid中,某些位为固定的字符
		uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-'
		uuid[14] = '4'

		for (let i = 0; i < 36; i++) {
			if (!uuid[i]) {
				r = 0 | Math.random() * 16
				uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r]
			}
		}
	}
	// 移除第一个字符,并用u替代,因为第一个字符为数值时,该guuid不能用作id或者class
	if (firstU) {
		uuid.shift()
		return `u${uuid.join('')}`
	}
	return uuid.join('')
}

#### 输了格式