how to import external library to nodejs

问题:

I would like to know how can I import an external library to nodejs. For example I would like to have phanotmjs library (I know that arelady exist an npm to get phantomjs, but is only an example).

I think that a way was to get the source file of library and include it into a module like that:

module.exports = function (name, cb) {
   //source code of library
});

But I think is a wrong way.

How can I include external library to nodejs project to use it inside it with its functionality?

Thanks

回答1:

Without exporting, a no elegant way is to copy past the entire library, in the bottom of your node file. nasty you may already thought about it. there is also a bad thing about that. you will not be able to reuse it in all different files.

The other way is to export the files along your workflow every time you need a function. And i think this is ok.

Otherwise to answer that, you can write the export this way:

module.exports = {
    removeElementFromArray_Mutate,
    hasClass,
    hasClass_ONEtest,
    removeClassFromAll,
    addClass,
    removeClass
};

you can do that with node. all of those are normal function declared this way:

function removeClassFromAll(DOMobject, classes){
    for(let i = 0; i < DOMobject.length; i++){
        removeClass(DOMobject[i], classes);
    }
}

function hasClass_ONEtest(DOMElement, classe) {
    let allClasses = DOMElement.className.split(/\s+/);
    for(let i = 0; i < allClasses.length; i++){
       if(allClasses[i].trim() === classe){
           return true;
       }
    }
    return false;
}

function hasClass(DOMElement, classes) {
    if (typeof classes === 'string') {
        return hasClass_ONEtest(DOMElement, classes);
    } else { // multiple classes as array
        for (let i = 0; i < classes.length; i++) {
            if (!hasClass_ONEtest(DOMElement, classes[i])) {
                return false;
            }
        }
        return true;
    }
}

this way you can write a quick script that parse all the file, and take out the definitions of the functions, if you can't do it manually. You can use regex, to speed up that. you need two patterns. the first for function name( and the second for name = function(. Hope that was helpful!

the question was more about if there is a way included with nodejs. There is none at the moment. it may be in the future. You may also see this How do I include a JavaScript file in another JavaScript file?. It may not help though.

回答2:

When one requires a module on nodejs, the content of module.exports is returned. So, one can return a function (as you do on your example) or an object, as in

in module.js:

module.exports={
    func:function(){ return true; },
    val:10,
    ...
}

So that, in the requiring file, you can:

 var m=require('module');

 assert(m.func()===true);
 assert(10===m.val);

This is explained in the nodejs documentation under Modules

So if you have an external JS library that exposes three functions: a, b, and c, you might wrap them as:

module.exports={
    exportedA:lib.a,
    exportedB:lib.b,
    exportedC:lib.c
};

lib.a=function(){ ... };

lib.b=function(){ ... };

lib.c=function(){ ... };