如果不可用则如何安装节点依赖Gulp + nodejs

Question

I am using Gulp to start a web application. I have the following basic code for my gulpfile.js:

var gulp = require('gulp'),
nodemon = require('gulp-nodemon');

gulp.task('default', function () {
  nodemon({
    script: 'server.js'
  , ext: 'js html'
  , env: { 'NODE_ENV': 'development' }
  })
})

Using Gulp, I want to check for dependencies and if they are not available then install them and then run 'script.js'. How can this be done?

I have the following package.json:

{
"name": "sample-project",
"version": "1.0.0",
"description": "Displays users and user details",
"main": "server.js",
"dependencies": {
"jquery"  : “>=1.5.1",
“bootstrap”: ">= 3.0.0”
}
"directories": {
"test": "test"
},
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "node server.js"
},
"author": "Arihant Jain",
"license": "ISC"
}

Answer 1

You can run npm install independently from an executing task using node's child_process as such:

var gulp = require('gulp');
var nodemon = require('gulp-nodemon');
var child_process = require('child_process');

gulp.task('default', function () {

    // Run npm install from the child process
    child_process.exe('npm install', function(err, stdout, stderr){

        // if everything goes well
        if(!err){

             // run nodemon
              nodemon({
                script: 'server.js'
              , ext: 'js html'
              , env: { 'NODE_ENV': 'development' }
              })

        }

    });
})

---

Given your requirement:

Using Gulp, I want to check for dependencies and if they are not available then install them...

That is exactly what npm install does. It checks the local package.json and proceeds to install missing packages.

Answer 2

So, I worked it around in a way by using gulp-run. I actually run the command npm install .

gulpfile looks like this:

        var gulp = require('gulp'),
        nodemon = require('gulp-nodemon')
        run = require('gulp-run')
        runSequence = require('run-sequence')
        open = require('gulp-open');

gulp.task('default', function() {
  runSequence('dependencies',
              'start',
              'uri');
});


      gulp.task('dependencies', function() {
  return run('npm install').exec();
})

    gulp.task('uri', function(){
  gulp.src(__filename)
  .pipe(open({uri: 'http://localhost:3000/index.html'}));
});



    gulp.task('start', function () {
  nodemon({
    script: 'server.js'
  , ext: 'js html'
  , env: { 'NODE_ENV': 'development' }
  })
})