I recently installed node.js and was told that express was the way to go for routing and getting set up with web application development.
I installed the latest version of node which apparently is incompatible with the latest express.
I looked up and found nave... Like RVM, nave allows you to switch versions of node. So I ran nave.sh install 0.4.11... That worked successfully and I was able to run.
npm install express -g
This I thought, should install express globally. So I run:
express testapp
which creates
create : testapp
create : testapp/package.json
create : testapp/app.js
create : testapp/public/stylesheets
create : testapp/public/stylesheets/style.css
create : testapp/public/images
create : testapp/public/javascripts
create : testapp/views
create : testapp/views/layout.jade
create : testapp/views/index.jade
Then I
cd testapp/
node app.js
I get
Error: Cannot find module 'express'
Is this usual behavior?
Since express is in packages.json, if I run npm install -d, it will create a node_modules directory in my application and not just symlink to the node_modules in my node path.
In a word, yes, this is the usual behavior.
When you install packages using NPM with -g option, it installs it globally, which does nice things like putting executeables on your path (i.e. the express script you used)
However, it does NOT put those packages anywhere that node can find them.
To install it so node can find the package, you must also do
cd "your express app"
npm install express
which installs locally (to the node_modules folder in the root of your application dir).
This is primarily to avoid any dependencies conflicts, and though it may seem silly, it is in fact really useful.
If you have some real reason to want to use your global install (say for example you have many applications that you want to make sure always share the same version) you can use the npm link command.
For a good rundown of NPM and global vs local see this blog post.
If you are on Windows, add location to your path.
export NODE_PATH="C:\Users\IMarek\AppData\Roaming\npm\node_modules"
Change: IMarek to your user name.
Related
I have installed the tar-module using
npm install -g tar
When I type
npm list -g --depth=0
I can see the entry tar#6.1.0 in the module-tree, however when I try to require it in a js-file const tar = require("tar"), I get the error message
Uncaught Exception:
Error: Cannot find module 'tar'
What am I missing?
The issue here is that you're trying to use something installed globally in a local project. You should be able to use your libraries if you install them inside the project with npm i tar.
The reason we install something globally is for use during development on many projects. This way, we don't have to install a tool on every project. With something you want to use inside a projects code however, you should install it on a project level. This way everything that the project needs to work lives inside of the project itself. You should see all dependencies listed inside of your package.json file
Not gonna advocate you do this, but if you really want to include the globally installed library, you can do something like this:
require('./../../.npm-global/lib/node_modules/tar'); // Relative path to library
Where you go up the file directory to your $HOME directory into the default global install location for node and bring it in. This is poor practice, please don't do it, but heres the info none-the-less.
I am starting to learn React Native and I am very new to npm package manager. I read that npm can install packages localy or globaly but I am trying to understand what does that mean.
I am reading this page https://docs.npmjs.com/getting-started/installing-npm-packages-locally, can someone explain to me what does this mean please.
If you want to depend on the package from your own module using something like Node.js' require, then you want to install locally, which is npm install's default behavior. On the other hand, if you want to use it as a command line tool, something like the grunt CLI, then you want to install it globally.
Since I am very new to npm, React Native, Node (never used it), I am confused by the very first sentence in this quote. What does it mean "my own module?
If I want to use CRNA, I guess, I would have to install it globally?
If I am to install a package, say CRNA locally or globally, where do I see it installed on my MacBook Pro?
The difference between local and global install is that local install puts it into the node_modules directory of your project (this is what is referred to as "your own module") while global puts it into a system directory (the exact location depends on your OS, on OSX it should be /usr/local/lib/node_modules).
Basically:
Local install ties the installed module to your project: other projects on your computer do not get it but if your project is copied to another computer the module will be installed there too
global install ties it to your computer: you can use it on all of
your projects on your computer but if your project is copied to
another computer the installed module will not be there
And yes, CRNA should be installed globally as it is a general tool not a project's library dependence.
When you install package globally npm install -g <package name> modules drops in {prefix}/lib/node_modules.
Locally - npm install <package name> - drops package in the current working directory.
If you are going to require module in your project you have to install it locally.
If you want to run in from command line you need to install it globally.
If you need more extenden explanation take a look
Since I am very new to npm, React Native, Node (never used it), I am confused by the very first sentence in this quote. What does it mean "my own module?
If you have package.json file, then everything in the same folder is treated as "module". You add dependencies to it by doing npm install --save foo (--save option adds it under dependencies in your package.json).
If I want to use CRNA, I guess, I would have to install it globally?
Not sure what "CRNA" is. But general rule is that mostly everything (libraries...) are installed locally. Which means that they are added to your package.json and installed in same folder under node_modules.
Only case when you want to install something globally (can be added to package.json but is NOT installed in the same folder under node_modules but probably in your home directory), by doing npm install --global bar (--global installs it globally). Is when tool (not library) is project independent, as you can access it from everywhere. Something like create-react-app.
TLDR:
Local are dependencies (libraries) installed in same folder and (usually) added in your package.json as dependencie.
Global are tools installed in your user home folder and (usually) NOT added in your package.json as dependencie.
Let first start with how nodejs finds package.
Suppose you have some folder structure like-
root
-pixel
-project1
-project2
So, if your are working on project1 and required some npm package, nodejs tries to find a folder named node_modules in current directory. If fails, it goes parent(pixel folder) and tries to find node_modules and goes recursively upto root(which is global).
So, if there any package installed globally, you don't need to install it in your current working directory.
So, why don't we install all packages globally? Isn't it saves our harddisk memory?
Yes, true. But as npm packages are updating and changing its version everytime, its necessary to use specific package in your current working package to avoid collusion.
Then how global packages is useful?
Its good idea to install some cli packages to run directly from command line i.e webpack to easy our task.
I have used to install my nodejs on D:\ drive instead of C and have set environment variables to D drive node & npm folders.
Then i changed npm installation path as "prefix=D:\node\node_modules\npm
" on "npmrc" file. So i could confirm that all user based modules are pointing on D drive npm folder instead of appdata.
I tried to install express js globally and i used to check the package tree on my cli as mentioned below,
npm ll -g
while trying this command am getting npm extraneous ERR,
Please suggest me that which way i have to use npm path and installation stuffs.
Thanks in advance.
It might seem like a good idea to install packages globally, but this is one great reason not to.
Often used packages like express, and cookies should be kept local to a package. Mostly because of versioning issues. You might have one package using express2, but your new one wants to use express3. You would have trouble if it was a global install. When in doubt leave off that -g, and use a --save instead. (This adds the package to your npm dependencies list.)
On the other hand, command line tools like mocha, yeoman, and uh not much else that I know of should be installed with the -g flag.
I'm not much of a windows person, so you'll have to look a little yourself, but I would also recommend not installing Node by hand, but instead using a version manager like nvm to do that stuff. Here's an nvm port for windows: https://github.com/coreybutler/nvm-windows
In my package.json file, I have bower listed as a dependency. After I run npm install, bower gets installed locally. When I try to run bower after installing it locally I get an error
"bower" is not recognized as an internal or external command
It seems the only way to resolve this is to install bower globally. Why should I have to do this? If my project contains a local copy of bower, why won't node use it?
Installing locally makes bower available to the current project (where it stores all of the node modules in node_modules). This is usually only good for using a module like so var module = require('module'); It will not be available as a command that the shell can resolve until you install it globally npm install -g module where npm will install it in a place where your path variable will resolve this command.
Edit: This documentation explains it pretty thorougly.
You can execute your local instance by typing the line below in cmd:
node_modules/bower/bin/bower <bower args>
We use both PHP and JavaScript, so we have composer and npm.
Each of the projects we work on have different packages both for runtime of the package as well as build/dev tools.
As there are version constraints in each project, installing version x of a package globally (that would be run from the command line), would cause us issues, we install all the tooling in each package. Much easier to define in the appropriate composer.json / package.json files.
But running the CLI tools is a pain if you have to constantly add an additional path to the command.
To that end, we have recommend to the team that the following paths are added to your $PATH in the appropriate .bashrc (or equivalent):
./vendor/bin:./node_modules/.bin
(EDIT: For Windows, the paths would be .\vendor\bin;.\node_modules\.bin;)
So, whilst in project X, we have access to the CLI tools for that project. Switch to project Y, and we get that projects tools.
Sure, you are going to get duplications, but each project is maintained by different teams (and some people are in multiple teams), so again, having 1 version in the global setup is an issue there.
Usually you install NPM modules globally if you want them included in your path to be ran from the command line. Since it is installed locally you will have to run it from the node_modules folder.
I want to experiment with some node.js stuff and I installed it yesterday following someone's instructions on the web which got it up and running, and I got the standard Hello World web page up on the screen.
I now went to move onto another example, but in order to not clutter my home directory, I created a directory off of it (~/node) and created the files I needed in there. Low and behold, when it came time to run the service, I got no joy stating the express module couldn't be found.
The instructions told me to install express using the -g flag, but that didn't help. I even ran it again without any luck.
Now I've found this:
Cannot find module `express` | socket.io [node.js]
and it appears I have to install it again under the current directory. I have done that and it works. Is it the case it has to be installed under each directory that I want services running from? It seems an unnecessary duplication.
edit:
Not knowing much about js I thought I would go digging and found
app.use(express['static'](__dirname ));
and have realised this is probably the cause of my problem. Further research has found this: http://nodejs.org/api/modules.html#modules_loading_from_node_modules_folders and if I install it once in a higher level directory, that should 'solve' my problem. I'm not going to bother about uninstalling the module, but for my next project I will try it and see how it goes.
I don't know why the original author suggested the -g flag when installing express, since it hasn't seemed to work for me.
NPM is a really nice tool, allowing you to install node.js modules locally and globally.
Local module installation
If you want to use a module for your project, you have to install it locally.
That's why npm creates a subdirectory called node_modules inside your project directory.
If you use the same module for two different projects, npm will download the module and install it twice. That's perfectly normal, it helps you manage different versions of the same dependency.
The best way to manage dependencies and install modules for a specific project is to fill the package.json with your dependencies and install them using
npm install
inside your project directory.
To access your modules in your code, use the require() function.
For example, with expressjs :
var express = require('express');
var app = express();
...
Global module installation
npm allows you to install modules globally as well. But remember that installing a module globally only provides more commands in your terminal, as with expressjs and express(1).
In order to install expressjs globally, run this in your terminal
npm install -g express
If you want to use a globally installed module in a specific project, you also have to install it locally (in your project directory, without -g).
I hope this answers clearly your question.
Express is capable of generating a simple app structure when installed globally. See this link and scroll to Using express(1) to generate an app section. It's a good way to get you started easily.
Take a look into package.json, package.json in nodejitsu
All npm packages contain a file, usually in the project root, called package.json - this file holds various metadata relevant to the project. This file is used to give information to npm that allows it to identify the project as well as handle the project's dependencies
a package.json example:
{
"name": "CRUD",
"description": "A simple CRUD",
"author": "Only for learn",
"dependencies": {
"express": "*",
},
}
so for install the dependencies go to level that package.json is, and run npm install this one will install all the dependencies you need for the project.
EDIT
a package.json interactive guide
I have found that when setting up node.js projects and dependencies, using Grunt [http://gruntjs.com/] has a lot of advantages. Although there are lots of different ways to setup a node and express project there is a lot to be said for using the Douglas Crockford approach and 'going with the grain'. In this case Grunt is the grain as it is becoming the de-facto standard for setting up a node project and there are existing templates for the most common types of node.js projects. You can find Grunt Express here [https://github.com/blai/grunt-express].
In this case Grunt would provide you with a project structure consistent with others, setup dependencies file for the node package manager and auto generate the express project for you. Packages are kept in a node_modules directory. If you are familiar with maven you might recognize the 'convention over configuration approach'.