function generate(count) {
var founded = false,
_sym = 'abcdefghijklmnopqrstuvwxyz1234567890',
str = '';
while(!founded) {
for(var i = 0; i < count; i++) {
str += _sym[parseInt(Math.random() * (_sym.length))];
}
base.getID(string, function(err, res) {
if(!res.length) {
founded = true; // How to do it?
}
});
}
return str;
}
如何设置一个变量值与数据库查询回调?我该怎么做呢?
安装NPM uuid包(来源:https://github.com/uuidjs/uuid):
npm install uuid
并在你的代码中使用它,例如ES6导入:
import { v4 as uuidv4, v6 as uuidv6 } from 'uuid';
uuidv4();
uuidv6();
或者使用CommonJS需要:
const {
v1: uuidv1,
v4: uuidv4,
} = require('uuid');
uuidv1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a'
uuidv4(); // -> '110ec58a-a0f2-4ac4-8393-c866d813b8d1'
For
如果有人需要加密强UUID,也有解决方案。
https://www.npmjs.com/package/generate-safe-id
npm install generate-safe-id
Why not UUIDs?
Random UUIDs (UUIDv4) do not have enough entropy to be universally
unique (ironic, eh?). Random UUIDs have only 122 bits of entropy,
which suggests that a duplicate will occur after only 2^61 IDs.
Additionally, some UUIDv4 implementations do not use a
cryptographically strong random number generator.
This library generates 240-bit IDs using the Node.js crypto RNG,
suggesting the first duplicate will occur after generating 2^120 IDs.
Based on the current energy production of the human race, this
threshold will be impossible to cross for the foreseeable future.
var generateSafeId = require('generate-safe-id');
var id = generateSafeId();
// id == "zVPkWyvgRW-7pSk0iRzEhdnPcnWfMRi-ZcaPxrHA"
我已经有一段时间没有使用node.js了,但我想我可能能帮上忙。
首先,在node中,你只有一个线程,并且应该使用回调。你的代码会发生什么,就是这个基础。getID查询将被排队等待执行,但while循环将继续作为繁忙循环毫无意义地运行。
你应该能够解决你的问题回调如下:
function generate(count, k) {
var _sym = 'abcdefghijklmnopqrstuvwxyz1234567890',
var str = '';
for(var i = 0; i < count; i++) {
str += _sym[parseInt(Math.random() * (_sym.length))];
}
base.getID(str, function(err, res) {
if(!res.length) {
k(str) // use the continuation
} else generate(count, k) // otherwise, recurse on generate
});
}
并这样使用它
generate(10, function(uniqueId){
// have a uniqueId
})
我在2年左右没有编写任何node/js,也没有测试过这个,但基本思想应该保持不变——不要使用繁忙循环,并使用回调。您可能想看一下节点异步包。