All callbacks are executing at the same time but why?

I'm currently wrapping an executable I've made with NodeJS. The executable can save strings for use in other processes within the executable. Each time the executable 'saves' a string it sends a pointer back to the server via stdout. The NodeJS server saves strings by sending them to stdin of the executable.

Originally I was writing code like this:

CLRProcess.stdout.once('data',function(strptr){
    CLRProcess.stdout.once('data', function(str){
         console.log(str.toString())
    })
    CLRProcess.stdin.write("StringReturn " + strptr.toString())
})
CLRProcess.stdin.write("StringInject __CrLf__ Mary had a__CrLf__little lamb.")

The above code injects a string

Mary had a
little lamb.

receives a pointer to the string, and then requests the string in the next step, by sending the pointer back to the host application.

To make coding algorithms easier I wanted a system like this:

strPtr = Exec("StringInject __CrLf__ Mary had a__CrLf__little lamb.")
str = Exec("StringReturn " + strPtr)
// do stuff with str

This is the code I made:

class Pointer {
    constructor(){
        this.value = undefined
        this.type = "ptr"
    }
}


class CLR_Events extends Array {
    constructor(CLR){
        super()
        this.CLR = CLR
    }
    runAll(){
        if(this.length>0){
            //Contribution by le_m: https://stackoverflow.com/a/44447739/6302131. See Contrib#1
            this.shift().run(this.runAll.bind(this))
        }
    }
    new(cmd,args,ret){
        var requireRun = !(this.length>0)   //If events array is initially empty, a run is required
        var e = new CLR_Event(cmd,args,ret,this.CLR)
        this.push(e)
        if(requireRun){
            this.runAll()
        }
    }
}

class CLR_Event {
    constructor(cmd,args,ret,CLR){
        this.command = cmd;
        this.args = args
        this.CLR = CLR
        this.proc = CLR.CLRProcess;
        this.ptr = ret
    }

    run(callback){
        //Implementing event to execute callback after some other events have been created.
        if(this.command == "Finally"){
            this.args[0]()
            console.log("Running Finally")
            return callback(null)
        }

        //Implementation for all CLR events.
        var thisEvent = this
        this.proc.stdout.once('data',function(data){
            this.read()
            data = JSON.parse(data.toString())
            thisEvent.ptr.value = data
            callback(data);
        })
        this.proc.stdin.write(this.command + " " + this._getArgValues(this.args).join(" ") + "\n");
    }
    _getArgValues(args){
        var newArgs = []
        this.args.forEach(
            function(arg){
                if(arg.type=='ptr'){
                    if(typeof arg.value == "object"){
                        newArgs.push(JSON.stringify(arg.value))
                    } else {
                        newArgs.push(arg.value)
                    }
                } else if(typeof arg == "object"){
                    newArgs.push(JSON.stringify(arg))
                } else {
                    newArgs.push(arg)
                }
            }
        )
        return newArgs  
    }
}

var CLR = {}
CLR.CLRProcess = require('child_process').spawn('DynaCLR.exe')
CLR.CLRProcess.stdout.once('data',function(data){
    if(data!="Ready for input."){
        CLR.CLRProcess.kill()
        CLR = undefined
        throw new Error("Cannot create CLR process")
    } else {
        console.log('CLR is ready for input...')
    }
})
CLR.Events = new CLR_Events(CLR)

//UDFs

CLR.StringInject = function(str,CrLf="__CLR-CrLf__"){
    var ptr = new Pointer
    this.Events.new("StringInject",[CrLf,str.replace(/\n/g,CrLf)],ptr) //Note CLR.exe requires arguments to be the other way round -- easier command line passing
    return ptr
}
CLR.StringReturn = function(ptr){
    var sRet = new Pointer
    this.Events.new("StringReturn",[ptr],sRet)
    return sRet
}

CLR.Finally = function(callback){
    this.Events.new("Finally",[callback])
}

I intended this to do the following:

1. Functions StringInject, StringReturn and Finally create events and append them to the Events array.
2. The runAll() function of the Events object, removes the first 'event' from its array and runs the run() function of the array, passing itself as a callback.
3. The run functions writes to stdin of the executable, waits for a response in stdout, appends the data to the passed in pointer and then executes the runAll() function passed to it.

This is what I don't understand... When executing the multiple string injections:

S_ptr_1 = CLR.StringInject("Hello world!")
S_ptr_2 = CLR.StringInject("Hello world!__CLR-CrLf__My name is Sancarn!")
S_ptr_3 = CLR.StringInject("Mary had a little lamb;And it's name was Doug!",";")

I get the following data:

S_ptr_1 = {value:123,type:'ptr'}
S_ptr_2 = {value:123,type:'ptr'}
S_ptr_3 = {value:123,type:'ptr'}

Where as the data should be:

S_ptr_1 = {value:1,type:'ptr'}
S_ptr_2 = {value:2,type:'ptr'}
S_ptr_3 = {value:3,type:'ptr'}

The only scenario I can think this would happen is if, in pseudocode, the following happenned:

CLRProcess.stdin.write("StringInject Val1")
CLRProcess.stdin.write("StringInject Val2")
CLRProcess.stdin.write("StringInject Val3")
CLRProcess.stdout.once('data') ==> S_ptr_1
CLRProcess.stdout.once('data') ==> S_ptr_2
CLRProcess.stdout.once('data') ==> S_ptr_3

But why? Am I overlooking something or is there something fundamentally wrong with this algorithm?

via Sancarn