Call a constructor function from an external .js file in node

Question

I have actually an html file that loads a couple of js files:

<script type="text/javascript" src="jop.js"></script>
<script type="text/javascript" src="script.js"></script>

My objective is to migrate both scripts to node.js to run them standalone (without browser).

About the js files:

-jop.js: Compiled using the emscripten tool, contains a constructor function.

-script.js: Is the program itself

jop.js file content (beggining lines):

var PROPModule = function(Module) {
  Module = Module || {};

var Module;if(!Module)Module=(typeof PROPModule!=="undefined"?PROPModule:null)||{};var moduleOverrides={};// file continues....

script.js file content (original beggining lines):

var PROP = {};                          // PROP global object 
PROP['preRun'] = prerun;                // Will be called before PROP runs, but after the Emscripten runtime has initialized
PROP['onRuntimeInitialized'] = main;    // Called when the Emscripten runtime has initialized
PROP['TOTAL_MEMORY'] = 64*1024*1024;    // PROP Heap defaults 
PROPModule(PROP);                       // Calling the constructor function with our object

I´ve trying to call the constructor function "PROPModule(PROP); " in script.js using 'require' but none of the approachs works. This way:

script.js (modified in node. Beggining lines):

var jopjs = require('./jop.js');
var PROP = {};
PROP['preRun'] = prerun;  
PROP['onRuntimeInitialized'] = main;
PROP['TOTAL_MEMORY'] = 64*1024*1024;
jopjs.PROPModule(PROP);    

ReferenceError: jopjs is not defined

I´m quite new with js and node, and I´ve been searching for several days a solution without success.

Any suggestion please or idea how to call this constructor?.

Answer 1

.js file is read differently in browser and in nodejs. Hence, most probably your.js (coded for browser) won't be read in nodejs environment, vice versa.

What I did to make my js file compatible to both is wrapping my js code with this script:

/** jop.js */
; (function (window, factory) {
    if (typeof exports === 'object') {
        module.exports = factory();     // NodeJs Environment
    } else {
        window.jop = factory();         // Browser Environment
    }
}(this, function () {
    return (function (window) {
        "use string";

        let PROPModule = function (Module) {
            console.log('PROPModule is called');
        }

        // exposed functions
        return { myFunc };
    }(this));

}));

While this is how you can import it in NodeJS environment:

script.js

const jopjs = require('./jop')

While this is how you can import it in browser environment (either inside or ):

<script type="text/javascript" src="./app/lokidb-seed.js"></script>
<script>
  console.log('The "jop" word in window.jop = factory();: ', jop.PROPModule());
</script>