How do I pass variables to powershell through node js

I'm trying to runs specific parameterized powershell scripts. Below is a working example

var spawn = require("child_process").spawn,child;

child = spawn("powershell.exe",["c:\\test\\mypstest.ps1 -arg1 1"]);
     child.stdout.on("data",function(data){
     console.log("Powershell Data: " + data);
});
     child.stderr.on("data",function(data){
     console.log("Powershell Errors: " + data);
});
child.on("exit",function(){
     console.log("Powershell Script finished");
});

child.stdin.end(); //end input

Here is an example ps script

param(
    [int]$arg1 = 0
    )

function test(){
    If ($arg1 -eq 0){
    write-host 'too bad'
    }

    If ($arg1 -eq 1){
        calc
    }

    If ($arg1 -eq 2){ 
        notepad
    }
}
test

But I need to be able to pass the variables as the arguments for the ps script. I thought this would work.

var str2 = "\"c:\\test\\mypstest.ps1 -arg1";
var str3 = " 1\"";

var mystr1 = str2.concat(str3);

child = spawn("powershell.exe",[mystr1]);

I also tried

function myfunc1(param1, param2){
    var mystr1 = str2.concat(str3);
    //console.log(mystr1);
    return mystr1;
    };

child = spawn("powershell.exe",[myfunc1(str2, str3)]);

But i appear to be passed back the variable itself, below is the output i get from the console

Powershell Data: c:\test\mypstest.ps1 -arg1 1

Powershell Script finished

And tried this

var str1 = "\"powershell.exe\"\,";
var str2 = "\[\"c:\\test\\mypstest.ps1 -arg1";
var str3 = " 1\"\]";

function myfunc1(param1, param2, param3){
    var mystr1 = str1.concat(str2, str3);
    console.log(mystr1);
    return mystr1;
    };

child = spawn(myfunc1(str1, str2, str3));

for the above i get an exception

events.js:72 throw er; // Unhandled 'error' event Error: spawn ENOENT at errnoException (child_process.js:998:11) at Process.ChildProcess._handle.onexit (child_process.js:789:34)

i'm not fluent in js so any help would be appreciated