hotreload.js

(function (){

const moduleDef = {
    "./a.tsx": {
        code: function (module, exports, require){  
            module.exports = 1  
        },
        parent: ["./b.tsx"]
    },
    "./b.tsx": {
        code: function (module, exports, require){
            function render(){
                console.log(require("./a.tsx") + 3)            
            }

            if(module.hot){
                module.hot.accept("./a.tsx",()=>{
                    render()
                })
            }else{
                render()
            }
        }
    }
}

const moduleCache = {}

function resolve(url, hot){
    if(hot || !(url in moduleCache)){
        const exports = {}
        let needBubble = !!hot
        const module = {
            exports,
            hot: hot ? {
                accept(url, callback){
                    needBubble = false
                    setTimeout(callback, 0)
                }
            } : false
        }
        moduleDef[url].code(module, exports, require)
        moduleCache[url] = module
        if(needBubble){
            const parentModules = moduleDef[url].parent
            if(!parentModules){
                console.warn("hot bubble failed")
                location.reload()
            }else{
                parentModules.forEach(url=>{
                    resolve(url, hot)
                })
            }
        }
    }
    return moduleCache[url]
}

function require(url){
    return resolve(url).exports
}


require("./b.tsx")

function hotUpdate(url, newCode){
    moduleDef[url].code = newCode
    resolve(url, true)
}

console.log('hot reloading...')

hotUpdate("./a.tsx", function(module, exports){
    module.exports = 3
})


})()