I'm trying to pass a lang variable in my js files.
Actually I have this:
<script src="assets/js/plugins.js?lang=en"></script>
In plugins.js, I have this:
var LIBS = {
// Chart libraries
validation: [
"assets/libs/validation/jquery.validation.min.js",
"assets/libs/validation/lang/xxxxxx.min.js"
],
...
};
How can I get the lang value passed to replace my xxxxxx by the lang en ?
Thanks.
try this in your plugin.js
var LIBS = {
// Chart libraries
validation: [
"assets/libs/validation/jquery.validation.min.js",
"assets/libs/validation/lang/xxxxxx.min.js"
]
};
LIBS.tmpValidation = LIBS.validation;
LIBS.validation = [];
LIBS.lang = "en";
Object.defineProperty(LIBS, "validation", {
get : function(){
var self = this;
return this.tmpValidation.map(function(item){
return item.replace(/xxxxxx/g, self.lang)
})
}
});
console.log(LIBS.validation);
You can now define your plugin in such a way that lang property is set to LIBS before invoking LIBS.validation
You can use a global variable.
Global variable:
I've used an object here to store settings, you could add more settings, if you wish
var settings = { lang:'en' };
Your other script (plugins.js):
var LIBS = {
// Chart libraries
validation: [
'assets/libs/validation/jquery.validation.min.js',
'assets/libs/validation/lang/' + settings.lang + '.min.js'
],
...
};
Here's a full example script that does precisely what I'm talking about above. I've got LIBS declared in the same script, but it could just as easily be included in plugins.js and declared below the setting of the global settings variable in this script instead...
Example Script:
<script>
var settings = { lang:'en' };
console.log(settings); // Show that the value has been set.
var LIBS = {
// Chart libraries
validation: [
'assets/libs/validation/jquery.validation.min.js',
'assets/libs/validation/lang/' + settings.lang + '.min.js'
]
};
// Show that LIBS has been set with the language setting from the global variable.
console.log(LIBS);
</script>
After you've run this, then you will see that the variable has been picked up and the second entry in the array is assets/libs/validation/lang/en.min.js
Or to be closer to your own example...
<script>
var settings = { lang:'en' };
console.log(settings); // Show that the value has been set.
</script>
<!-- Following line must come after the script above
this JS file can now access that global settings variable -->
<script src="plugins.js"></script>
try
var s = document.getElementsByTagName('script'),
ss = s[s.length-1];
lang = ss.src.match(/\?lang=(\w\w)/);
// sure... check it exists!
console.debug(lang[1]);
inside plugins.js
Let's say I have a file called app.js. Pretty simple:
var express = require('express');
var app = express.createServer();
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');
app.get('/', function(req, res){
res.render('index', {locals: {
title: 'NowJS + Express Example'
}});
});
app.listen(8080);
What if I have a functions inside "tools.js". How would I import them to use in apps.js?
Or...am I supposed to turn "tools" into a module, and then require it? << seems hard, I rather do the basic import of the tools.js file.
You can require any js file, you just need to declare what you want to expose.
// tools.js
// ========
module.exports = {
foo: function () {
// whatever
},
bar: function () {
// whatever
}
};
var zemba = function () {
}
And in your app file:
// app.js
// ======
var tools = require('./tools');
console.log(typeof tools.foo); // => 'function'
console.log(typeof tools.bar); // => 'function'
console.log(typeof tools.zemba); // => undefined
If, despite all the other answers, you still want to traditionally include a file in a node.js source file, you can use this:
var fs = require('fs');
// file is included here:
eval(fs.readFileSync('tools.js')+'');
The empty string concatenation +'' is necessary to get the file content as a string and not an object (you can also use .toString() if you prefer).
The eval() can't be used inside a function and must be called inside the global scope otherwise no functions or variables will be accessible (i.e. you can't create a include() utility function or something like that).
Please note that in most cases this is bad practice and you should instead write a module. However, there are rare situations, where pollution of your local context/namespace is what you really want.
Update 2015-08-06
Please also note this won't work with "use strict"; (when you are in "strict mode") because functions and variables defined in the "imported" file can't be accessed by the code that does the import. Strict mode enforces some rules defined by newer versions of the language standard. This may be another reason to avoid the solution described here.
You need no new functions nor new modules.
You simply need to execute the module you're calling if you don't want to use namespace.
in tools.js
module.exports = function() {
this.sum = function(a,b) { return a+b };
this.multiply = function(a,b) { return a*b };
//etc
}
in app.js
or in any other .js like myController.js :
instead of
var tools = require('tools.js') which force us to use a namespace and call tools like tools.sum(1,2);
we can simply call
require('tools.js')();
and then
sum(1,2);
in my case I have a file with controllers ctrls.js
module.exports = function() {
this.Categories = require('categories.js');
}
and I can use Categories in every context as public class after require('ctrls.js')()
Create two js files
// File cal.js
module.exports = {
sum: function(a,b) {
return a+b
},
multiply: function(a,b) {
return a*b
}
};
Main js file
// File app.js
var tools = require("./cal.js");
var value = tools.sum(10,20);
console.log("Value: "+value);
Console Output
Value: 30
create two files e.g app.js and tools.js
app.js
const tools= require("./tools.js")
var x = tools.add(4,2) ;
var y = tools.subtract(4,2);
console.log(x);
console.log(y);
tools.js
const add = function(x, y){
return x+y;
}
const subtract = function(x, y){
return x-y;
}
module.exports ={
add,subtract
}
output
6
2
Here is a plain and simple explanation:
Server.js content:
// Include the public functions from 'helpers.js'
var helpers = require('./helpers');
// Let's assume this is the data which comes from the database or somewhere else
var databaseName = 'Walter';
var databaseSurname = 'Heisenberg';
// Use the function from 'helpers.js' in the main file, which is server.js
var fullname = helpers.concatenateNames(databaseName, databaseSurname);
Helpers.js content:
// 'module.exports' is a node.JS specific feature, it does not work with regular JavaScript
module.exports =
{
// This is the function which will be called in the main file, which is server.js
// The parameters 'name' and 'surname' will be provided inside the function
// when the function is called in the main file.
// Example: concatenameNames('John,'Doe');
concatenateNames: function (name, surname)
{
var wholeName = name + " " + surname;
return wholeName;
},
sampleFunctionTwo: function ()
{
}
};
// Private variables and functions which will not be accessible outside this file
var privateFunction = function ()
{
};
I was also looking for a NodeJS 'include' function and I checked the solution proposed by Udo G - see message https://stackoverflow.com/a/8744519/2979590. His code doesn't work with my included JS files.
Finally I solved the problem like that:
var fs = require("fs");
function read(f) {
return fs.readFileSync(f).toString();
}
function include(f) {
eval.apply(global, [read(f)]);
}
include('somefile_with_some_declarations.js');
Sure, that helps.
Create two JavaScript files. E.g. import_functions.js and main.js
1.) import_functions.js
// Declaration --------------------------------------
module.exports =
{
add,
subtract
// ...
}
// Implementation ----------------------------------
function add(x, y)
{
return x + y;
}
function subtract(x, y)
{
return x - y;
}
// ...
2.) main.js
// include ---------------------------------------
const sf= require("./import_functions.js")
// use -------------------------------------------
var x = sf.add(4,2);
console.log(x);
var y = sf.subtract(4,2);
console.log(y);
output
6
2
The vm module in Node.js provides the ability to execute JavaScript code within the current context (including global object). See http://nodejs.org/docs/latest/api/vm.html#vm_vm_runinthiscontext_code_filename
Note that, as of today, there's a bug in the vm module that prevenst runInThisContext from doing the right when invoked from a new context. This only matters if your main program executes code within a new context and then that code calls runInThisContext. See https://github.com/joyent/node/issues/898
Sadly, the with(global) approach that Fernando suggested doesn't work for named functions like "function foo() {}"
In short, here's an include() function that works for me:
function include(path) {
var code = fs.readFileSync(path, 'utf-8');
vm.runInThisContext(code, path);
}
say we wants to call function ping() and add(30,20) which is in lib.js file
from main.js
main.js
lib = require("./lib.js")
output = lib.ping();
console.log(output);
//Passing Parameters
console.log("Sum of A and B = " + lib.add(20,30))
lib.js
this.ping=function ()
{
return "Ping Success"
}
//Functions with parameters
this.add=function(a,b)
{
return a+b
}
Udo G. said:
The eval() can't be used inside a function and must be called inside
the global scope otherwise no functions or variables will be
accessible (i.e. you can't create a include() utility function or
something like that).
He's right, but there's a way to affect the global scope from a function. Improving his example:
function include(file_) {
with (global) {
eval(fs.readFileSync(file_) + '');
};
};
include('somefile_with_some_declarations.js');
// the declarations are now accessible here.
Hope, that helps.
app.js
let { func_name } = require('path_to_tools.js');
func_name(); //function calling
tools.js
let func_name = function() {
...
//function body
...
};
module.exports = { func_name };
It worked with me like the following....
Lib1.js
//Any other private code here
// Code you want to export
exports.function1 = function(params) {.......};
exports.function2 = function(params) {.......};
// Again any private code
now in the Main.js file you need to include Lib1.js
var mylib = requires('lib1.js');
mylib.function1(params);
mylib.function2(params);
Please remember to put the Lib1.js in node_modules folder.
Another way to do this in my opinion, is to execute everything in the lib file when you call require() function using (function(/* things here */){})(); doing this will make all these functions global scope, exactly like the eval() solution
src/lib.js
(function () {
funcOne = function() {
console.log('mlt funcOne here');
}
funcThree = function(firstName) {
console.log(firstName, 'calls funcThree here');
}
name = "Mulatinho";
myobject = {
title: 'Node.JS is cool',
funcFour: function() {
return console.log('internal funcFour() called here');
}
}
})();
And then in your main code you can call your functions by name like:
main.js
require('./src/lib')
funcOne();
funcThree('Alex');
console.log(name);
console.log(myobject);
console.log(myobject.funcFour());
Will make this output
bash-3.2$ node -v
v7.2.1
bash-3.2$ node main.js
mlt funcOne here
Alex calls funcThree here
Mulatinho
{ title: 'Node.JS is cool', funcFour: [Function: funcFour] }
internal funcFour() called here
undefined
Pay atention to the undefined when you call my object.funcFour(), it will be the same if you load with eval(). Hope it helps :)
You can put your functions in global variables, but it's better practice to just turn your tools script into a module. It's really not too hard – just attach your public API to the exports object. Take a look at Understanding Node.js' exports module for some more detail.
I just want to add, in case you need just certain functions imported from your tools.js, then you can use a destructuring assignment which is supported in node.js since version 6.4 - see node.green.
Example:
(both files are in the same folder)
tools.js
module.exports = {
sum: function(a,b) {
return a + b;
},
isEven: function(a) {
return a % 2 == 0;
}
};
main.js
const { isEven } = require('./tools.js');
console.log(isEven(10));
output: true
This also avoids that you assign those functions as properties of another object as its the case in the following (common) assignment:
const tools = require('./tools.js');
where you need to call tools.isEven(10).
NOTE:
Don't forget to prefix your file name with the correct path - even if both files are in the same folder, you need to prefix with ./
From Node.js docs:
Without a leading '/', './', or '../' to indicate a file, the module
must either be a core module or is loaded from a node_modules folder.
Include file and run it in given (non-global) context
fileToInclude.js
define({
"data": "XYZ"
});
main.js
var fs = require("fs");
var vm = require("vm");
function include(path, context) {
var code = fs.readFileSync(path, 'utf-8');
vm.runInContext(code, vm.createContext(context));
}
// Include file
var customContext = {
"define": function (data) {
console.log(data);
}
};
include('./fileToInclude.js', customContext);
Using the ESM module system:
a.js:
export default function foo() {};
export function bar() {};
b.js:
import foo, {bar} from './a.js';
This is the best way i have created so far.
var fs = require('fs'),
includedFiles_ = {};
global.include = function (fileName) {
var sys = require('sys');
sys.puts('Loading file: ' + fileName);
var ev = require(fileName);
for (var prop in ev) {
global[prop] = ev[prop];
}
includedFiles_[fileName] = true;
};
global.includeOnce = function (fileName) {
if (!includedFiles_[fileName]) {
include(fileName);
}
};
global.includeFolderOnce = function (folder) {
var file, fileName,
sys = require('sys'),
files = fs.readdirSync(folder);
var getFileName = function(str) {
var splited = str.split('.');
splited.pop();
return splited.join('.');
},
getExtension = function(str) {
var splited = str.split('.');
return splited[splited.length - 1];
};
for (var i = 0; i < files.length; i++) {
file = files[i];
if (getExtension(file) === 'js') {
fileName = getFileName(file);
try {
includeOnce(folder + '/' + file);
} catch (err) {
// if (ext.vars) {
// console.log(ext.vars.dump(err));
// } else {
sys.puts(err);
// }
}
}
}
};
includeFolderOnce('./extensions');
includeOnce('./bin/Lara.js');
var lara = new Lara();
You still need to inform what you want to export
includeOnce('./bin/WebServer.js');
function Lara() {
this.webServer = new WebServer();
this.webServer.start();
}
Lara.prototype.webServer = null;
module.exports.Lara = Lara;
You can simple just require('./filename').
Eg.
// file: index.js
var express = require('express');
var app = express();
var child = require('./child');
app.use('/child', child);
app.get('/', function (req, res) {
res.send('parent');
});
app.listen(process.env.PORT, function () {
console.log('Example app listening on port '+process.env.PORT+'!');
});
// file: child.js
var express = require('express'),
child = express.Router();
console.log('child');
child.get('/child', function(req, res){
res.send('Child2');
});
child.get('/', function(req, res){
res.send('Child');
});
module.exports = child;
Please note that:
you can't listen PORT on the child file, only parent express module has PORT listener
Child is using 'Router', not parent Express moudle.
Node works based on commonjs modules and more recently, esm modules. Basically, you should create modules in separated .js files and make use of imports/exports (module.exports and require).
Javascript on the browser works differently, based on scope. There is the global scope, and through clojures (functions inside other functions) you have private scopes.
So,in node, export functions and objects that you will consume in other modules.
The cleanest way IMO is the following, In tools.js:
function A(){
.
.
.
}
function B(){
.
.
.
}
module.exports = {
A,
B
}
Then, in app.js, just require the tools.js as following: const tools = require("tools");
I was as well searching for an option to include code without writing modules, resp. use the same tested standalone sources from a different project for a Node.js service - and jmparattes answer did it for me.
The benefit is, you don't pollute the namespace, I don't have trouble with "use strict"; and it works well.
Here a full sample:
Script to load - /lib/foo.js
"use strict";
(function(){
var Foo = function(e){
this.foo = e;
}
Foo.prototype.x = 1;
return Foo;
}())
SampleModule - index.js
"use strict";
const fs = require('fs');
const path = require('path');
var SampleModule = module.exports = {
instAFoo: function(){
var Foo = eval.apply(
this, [fs.readFileSync(path.join(__dirname, '/lib/foo.js')).toString()]
);
var instance = new Foo('bar');
console.log(instance.foo); // 'bar'
console.log(instance.x); // '1'
}
}
Hope this was helpfull somehow.
Like you are having a file abc.txt and many more?
Create 2 files: fileread.js and fetchingfile.js, then in fileread.js write this code:
function fileread(filename) {
var contents= fs.readFileSync(filename);
return contents;
}
var fs = require("fs"); // file system
//var data = fileread("abc.txt");
module.exports.fileread = fileread;
//data.say();
//console.log(data.toString());
}
In fetchingfile.js write this code:
function myerror(){
console.log("Hey need some help");
console.log("type file=abc.txt");
}
var ags = require("minimist")(process.argv.slice(2), { string: "file" });
if(ags.help || !ags.file) {
myerror();
process.exit(1);
}
var hello = require("./fileread.js");
var data = hello.fileread(ags.file); // importing module here
console.log(data.toString());
Now, in a terminal:
$ node fetchingfile.js --file=abc.txt
You are passing the file name as an argument, moreover include all files in readfile.js instead of passing it.
Thanks
Another method when using node.js and express.js framework
var f1 = function(){
console.log("f1");
}
var f2 = function(){
console.log("f2");
}
module.exports = {
f1 : f1,
f2 : f2
}
store this in a js file named s and in the folder statics
Now to use the function
var s = require('../statics/s');
s.f1();
s.f2();
To turn "tools" into a module, I don't see hard at all. Despite all the other answers I would still recommend use of module.exports:
//util.js
module.exports = {
myFunction: function () {
// your logic in here
let message = "I am message from myFunction";
return message;
}
}
Now we need to assign this exports to global scope (in your app|index|server.js )
var util = require('./util');
Now you can refer and call function as:
//util.myFunction();
console.log(util.myFunction()); // prints in console :I am message from myFunction
To interactively test the module ./test.js in a Unix environment, something like this could be used:
>> node -e "eval(''+require('fs').readFileSync('./test.js'))" -i
...
Use:
var mymodule = require("./tools.js")
app.js:
module.exports.<your function> = function () {
<what should the function do>
}
Does anyone know what the pattern is for being able to create a module pattern but with being able to set the name space that the module lives under dynamically.
So instead of what is below:-
var MODULE = (function () {
var my = {},
privateVariable = 1;
function privateMethod() {
// ...
}
my.moduleProperty = 1;
my.moduleMethod = function () {
// ...
};
return my;
}());
MODULE could be set to anything you like, I remember seeing it done i a screencast but can't remember where...
Basically i'd like to create a library that could be assigned to any namespace the implementer likes.
I'd think you'd just be able to add a method that lets you set it, and nullify MODULE.
http://jsfiddle.net/yrsdR/
my.namespace = function( ns ) {
window[ns] = my;
window.MODULE = null;
}
then:
window.MODULE.namespace( "myNamespace" );
window.MODULE; // null
window.myNamespace // object
or you could have it return the module to whatever variable you want.
http://jsfiddle.net/yrsdR/1/
my.namespace = function() {
window.MODULE = null;
return my;
}
window.myNamespace = MODULE.namespace();
window.MODULE; // null
window.myNamespace // object
Funny to come across this now, I just set up a new code base this way. This is how I approached it (it depends on 1 extra global variable however):
// ability to rename namespace easily
var AXS_NS = 'App';
window[AXS_NS] = (function (app, $, Modernizr) {
app.config = {
debug: false
};
app.init = function() {
console.log('init');
};
return app;
})(window[AXS_NS] || {}, jQuery, Modernizr);
Then you could do:
jQuery(function($){
App.init();
});
I know this is a long ways after the original question. And I'm not sure of the relevance of having a dynamically named javascript object. But the following pattern does this is a reasonable way by allowing you to set up the object namespace name in the script element of your html page.
Something like
<script src="js/myscript.js" namespaceName="myObject"><script>
Which allows you to then call myObject.hello() in your javascript.
Example javascript that uses this solution.
/**
* Dynamic mechanism for setting a javascript namespace.
*
* This works by adding the namespaceName as an attribute to the script
* element on your page. Something like
*
* **<script src="js/myscript.js" namespaceName="myObject"><script>**
*
* When the script has loaded it will have created a new javascript object
* with the nemespace name "myObject".
*
* You can now use myObject.hello() which returns "ns.hello() called"<br/>
*
* This works on later versions of chrome, firefox and ie.
*/
(function (ns) {
ns.hello = function () {
return "ns.hello() called";
}
} (window[document.getElementsByTagName('script')[document.getElementsByTagName('script').length-1].attributes['namespaceName'].value]=
window[document.getElementsByTagName('script')[document.getElementsByTagName('script').length-1].attributes['namespaceName'].value] || {}));
The
window[document.getElementsByTagName('script')
[document.getElementsByTagName('script').length-1]
.attributes['namespaceName'].value]
Is used to pull the attribute namespaceName value from the script load