require-node

A node middleware let that browser js code can require node js code which is still running at node server

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require-node: In client(eg: Browser), you can REQUIRE and CALL server side javascript which is still running at server(eg: Node.js).

require-node 让您能在前端（比如：浏览器）require后端javascript代码并调用，而这些后端代码在执行时依然在服务器上执行，而非浏览器里。

For example: A javascript module(test.js) in Node server, you can require and call that in Browser, like this:

比如：您在Node服务器有一个模块test.js，您可以在浏览器中如下引用并调用：

In Browser code :
``
var test = require('path/to/test.js')

var sum = await test.add(1, 2) // sum = 3
var env = await test.getNodeEnv() // env is server env value
`
In Node server code (test.js) :
`
exports.add = function (a, b) {
return a + b;
}

exports.getNodeEnv = function () {
return process.env;
}
`
Note: also support promise、async/await and import grammar.

Installion

`
$ npm install require-node
`

Use

middleware: function (req, res, next) { ... }
`
var requireNode = require('require-node')
var middleware = requireNode({ base: "path/to/server" })
`

You can use this middleware in node HTTP :
`
require('http').createServer(function (req, res) {
middleware(req, res, function () {
//req that require-node not process
}
})
`

also, you can use this middleware in node EXPRESS :
`
var express = require('express')
var app = express()
app.use(middleware)
`

or, you can use this middleware in node KOA :
`
var Koa = require('koa')
var app = new Koa()
app.use((ctx, next) => {
var { req, res, body } = ctx;
req.body = body;
return middleware(req, res, next);
})
`

---

Config options

1. base: '/path/to/server', ONLY this config is necessary!
> Config which back end file or dir can be use in front end. base can be set String/Array/Object.

2. path: '/require-node' (default)
> Config which url path to be use sending ajax.

3. isDebug: false (default)
> Config require-node output log or not.

4. hook function
> Sometimes, for some reason(example: security or login), we will prevent some function calls. For each http request before processing, require-node calls preFetch in Browser and calls preCall in Node Server (if throw error or return promise reject, call will be prevent), after server api function called, postCall will be call in Node Server and postFetch alse be call in Browser.

preFetch: function (options) { return promise or common value; }
preCall: function (options) { return promise or common value; }
postCall: function (apiReturn, options) { return a new apiReturn; }
postFetch: function (apiReturn, options) { return a new apiReturn; }

options's structure: { req, res, moduleName, functionNames, formalParams, actualParams }
Note: In Browser, req is xhr(XMLHttpRequest) object.

5. inject: function(req, res){ return {curUser: req.session && req.session.curUser}; }
> Use inject config, you can define Custom Injected Services. For more details, please refer to the next section: Inject Service.

Inject Service

1. Use Default Service

If your back end function want use variable $req、$res、$session、http $body, you can define back end function like this:
`
function say(arg1, arg2, $req, arg4, arg5){
console.log($req) // $req is node http req object
}
exports.say = say
`
require-node will inject variable req to $req.

2. Use Custom Service

If want define Custom Injected Services, you can config like this(eg: curUser service):
`
var middleware = require('require-node')({
base: "path/to/server"
inject: function(req, res){
return {
curUser: req.session && req.session.currentUser, //if you store currentUser in req.session
otherService: ...
}
}
})
`
In your back end function, you can use curUser like this:
`
function say(arg1, arg2, curUser, arg4, arg5){
console.log(curUser)
}
exports.say = say
`

That's all.

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Example for how to use require-node` in https://github.com/luoshaohua/require-node-example