i got two javascript objects api and myApi :
var api = {};
api.foo = function(){ ... };
api.foo2 = function(){ ... };
var myApi = {};
myApi.foo = function(){ ...};
myApi.myFoo = function(){ ...};
myApi.myFoo2 = function(){ ...};
i want to add all myApi.* functions to api object without overriding api.foo.
Indeed, i want learn how to extend APIs to each other and developing plugins with javascript.
What are the best practices in this subject?
To answer the first part of your question, you can modify the merge method I use in some of my code:
if (typeof Object.merge !== 'function') {
Object.merge = function (o1, o2) { // Function to merge all of the properties from one object into another
for(var i in o2) { o1[i] = o2[i]; }
return o1;
};
}
To not overwrite preexisting objects, you would have to add a check:
if (typeof Object.merge !== 'function') {
Object.merge = function (o1, o2) { // Function to merge all of the properties from one object into another
for(var i in o2) { if(!(i in o1)) o1[i] = o2[i]; }
return o1;
};
}
Related
spec.js
describe('Testing an animal adoption flow using page object', function() {
beforeEach(function() {
browser.get('http://www.thetestroom.com/jswebapp/index.html');
});
var home_page = require('./pages/home_page.js');
it ('Should be able to adopt an animal by page object', function() {
home_page.enterName('Blabla');
expect(home_page.getDynamicText()).toBe('Blabla');
var animal_page = home_page.clickContinue();
animal_page.selectAnimal(1);
var confirm_page = animal_page.clickContinue();
expect(confirm_page.getTitle()).toContain('Thank');
});
});
home_page.js
require('./animal_page.js');
var home_page = function() {
this.nameTextBox = element(by.model('person.name'));
this.dynamicText = element(by.binding('person.name'));
this.continueButton = element(by.buttonText('CONTINUE'));
this.enterName = function(name) {
this.nameTextBox.sendKeys(name);
};
this.getDynamicText = function() {
return this.dynamicText.getText();
};
this.clickContinue = function() {
this.continueButton.click();
return require('./animal_page.js');
};
};
Failures:
Testing an animal adoption flow using page object Should be able to adopt an animal by page object
Message:
[31m Failed: home_page.enterName is not a function[0m
Stack:
TypeError: home_page.enterName is not a function
You don't create an instance of your constructor function with new keyword. It should have been
var home_page = new (require('./pages/home_page.js'));
and you need to instruct js what you are exporting, so your home page should be
require('./animal_page.js');
var home_page = function() {
this.nameTextBox = element(by.model('person.name'));
this.dynamicText = element(by.binding('person.name'));
this.continueButton = element(by.buttonText('CONTINUE'));
this.enterName = function(name) {
this.nameTextBox.sendKeys(name);
};
this.getDynamicText = function() {
return this.dynamicText.getText();
};
this.clickContinue = function() {
this.continueButton.click();
return require('./animal_page.js');
};
}
module.exports = home_page; // <------ this line
but make sure you do the same with animal_page
I got the answer, we need to include
spec.js
const { browser } = require('protractor');
home_page.js
module.exports = new home_page();
I created a service called AppService.
Its function getUserPostionOptions is supposed to return an object:
getUserPostionOptions: function (user) {
// PositionOptions.findOne({id:'53f218deed17760200778cfe'}).exec(function (err, positionOptions) {
var positionDirectionsOptions = [1,2,3];
var positionLengthsOptions = [4,5,6];
var object = {
directions:positionDirectionsOptions,
lengths:positionLengthsOptions
};
return object;
// });
}
This works, in my controller positionOptions gets populated correctly:
var positionOptions = AppService.getUserPostionOptions(user);
However, when I uncomment the find query the item is found but the object returns undefined.
Thank in advance for your help
SailsJs ORM (and almost NodeJs database querying methods) uses non-blocking mechanism via callback function. So you have to change your code into:
getUserPostionOptions: function (user, callback) {
PositionOptions.findOne({id:'53f218deed17760200778cfe'}).exec(function (err, positionOptions) {
var positionDirectionsOptions = [1,2,3];
var positionLengthsOptions = [4,5,6];
var object = {
directions:positionDirectionsOptions,
lengths:positionLengthsOptions
};
callback(null, object); // null indicates that your method has no error
});
}
Then just use it:
AppService.getUserPostionOptions(user, function(err, options) {
if (!err) {
sails.log.info("Here is your received data:");
sails.log.info(options);
}
});
I'm trying to create a list with endless scroll in angularjs. For this I need to fetch new data from an api and then append it to the existing results of a scope in angularjs. I have tried several methods, but none of them worked so far.
Currently this is my controller:
userControllers.controller('userListCtrl', ['$scope', 'User',
function($scope, User) {
$scope.users = User.query();
$scope.$watch('users');
$scope.orderProp = 'name';
window.addEventListener('scroll', function(event) {
if (document.body.offsetHeight < window.scrollY +
document.documentElement.clientHeight + 300) {
var promise = user.query();
$scope.users = $scope.users.concat(promise);
}
}, false);
}
]);
And this is my service:
userServices.factory('User', ['$resource',
function($resource) {
return $resource('api/users', {}, {
query: {
method: 'GET',
isArray: true
}
});
}
]);
How do I append new results to the scope instead of replacing the old ones?
I think you may need to use $scope.apply()
When the promise returns, because it isnt
Part of the angular execution loop.
Try something like:
User.query().then(function(){
$scope.apply(function(result){
// concat new users
});
});
The following code did the trick:
$scope.fetch = function() {
// Use User.query().$promise.then(...) to parse the results
User.query().$promise.then(function(result) {
for(var i in result) {
// There is more data in the result than just the users, so check types.
if(result[i] instanceof User) {
// Never concat and set the results, just append them.
$scope.users.push(result[i]);
}
}
});
};
window.addEventListener('scroll', function(event) {
if (document.body.offsetHeight < window.scrollY +
document.documentElement.clientHeight + 300) {
$scope.fetch();
}
}, false);
How do I manage batch save in Mongoose? I saw it may not be possible yet:
How can I save multiple documents concurrently in Mongoose/Node.js?
Theres some mention about using some flow control library like q, but I also notice there promises in mongoose, can it be used? Can I do like in jQuery Deferred/Promises
$.when(obj1.save(), obj2.save(), obj3.save()).then ->
# do something?
Yes, you can do this with promises. If you were using the Q promise library, you could re-write #matz3's code like:
var tasks = [];
for (var i=0; i < docs.length; i++) {
tasks.push(docs[i].save());
}
Q.all(tasks)
.then(function(results) {
console.log(results);
}, function (err) {
console.log(err);
});
We start all the operations one at a time in the loop, but we don't wait for any of them to complete, so they run in parallel. We add a promise (that acts like a placeholder for the result) to an array. We then wait for all the promises in the array of promises to complete.
Most good Promises/A+ compatible libraries have some equivalent to Q.all
mongoose now allows you to choose which Promise implementation.
Here I am using the node.js default system Promise (ES6) baked into nodejs
var mongoose = require('mongoose');
mongoose.Promise = global.Promise; // use system implementation
Promise.all(obj1.save(), obj2.save(), obj3.save())
.then(function(resultSaves) {
console.log('parallel promise save result :');
console.log(resultSaves);
mongoose.disconnect();
}).catch(function(err) {
console.log('ERROR on promise save :');
console.log(err);
mongoose.disconnect();
});
node --version
v4.1.1
mongoose#4.1.8
Since mongoose now supports promises you may use Promise.all().then(), so it will return when all promises are resolved.
Promise.all([
obj1.save(),
obj2.save(),
obj3.save()
])
.then(console.log)
.catch(console.error)
In fact, if you're always calling the save() method you can use the Array.map() here:
Promise.all([ obj1, obj2, obj3 ].map( obj => obj.save() )
Aaand also use es6 syntax to destructure the resulting array:
Promise.all(
[ obj1, obj2, obj3 ]
.map( obj => obj.save() )
)
.then( ([ savedObj1, savedObj2, savedObj3 ]) => {
// do something with your saved objects...
})
Try the parallel function of the async module.
var functions = [];
for (var i=0; i < docs.length; i++) {
functions.push((function(doc) {
return function(callback) {
doc.save(callback);
};
})(docs[i]));
}
async.parallel(functions, function(err, results) {
console.log(err);
console.log(results);
});
To save multiple mongoose docs in parallel, you can do something simple like this (assuming you have an array named docs of documents to save):
var count = docs.length;
docs.forEach(function(doc) {
doc.save(function(err, result) {
if (--count === 0) {
// All done; call containing function's callback
return callback();
}
});
});
A refined example on how to use async parallel would be:
async.parallel([obj1.save, obj2.save, obj3.save], callback);
Since the convention is the same in Mongoose as in async (err, callback) you don't need to wrap them in your own callbacks, just add your save calls in an array and you will get a callback when all is finished.
What about async.queue.
A simple example:
var queue = async.queue(function(obj, callback) {
return obj.save(callback);
});
for (var i in objs) {
var obj = objs[i];
// Some changes on object obj
queue.push(obj);
}
If you need a callback after the queue is emptied:
var emptyQueue = true;
var queue = async.queue(function(obj, callback) {
return obj.save(callback);
});
queue.drain = function() {
// Every callbacks are finished
// bigCallback();
};
for (var i in objs) {
var obj = objs[i];
// Some changes on object obj
queue.push(obj);
emptyQueue = false;
}
if (emptyQueue) {
// Call manually queue drain in case of the queue is empty
// and we need to call bigCallback() for example
return queue.drain();
}
#ForbesLindesay Why loading an external library when you can use mongoose implementation of promises and create your own All ?
Create a module that enhance mongoose promise with all.
var Promise = require("mongoose").Promise;
Promise.all = function(promises) {
var mainPromise = new Promise();
if (promises.lenght == 0) {
mainPromise.resolve(null, promises);
}
var pending = 0;
promises.forEach(function(p, i) {
pending++;
p.then(function(val) {
promises[i] = val;
if (--pending === 0) {
mainPromise.resolve(null, promises);
}
}, function(err) {
mainPromise.reject(err);
});
});
return mainPromise;
}
module.exports = Promise;
Then use it with mongoose:
require('./promise')
...
var tasks = [];
for (var i=0; i < docs.length; i++) {
tasks.push(docs[i].save());
}
mongoose.Promise.all(tasks)
.then(function(results) {
console.log(results);
}, function (err) {
console.log(err);
});
I have an existing node.js app where users have a library of files that are stored with GridFS. Each user has their own library. I would like to make the library mountable with WebDAV so that a user could manage their library from their desktop.
I have seen jsDAV used to access the filesystem but it is not clear how to extend it for use with a virtual file system. I found gitDav but it is not clear how to use it.
Is this even possible without starting from scratch?
I was looking to use jsDAV to make some resources available through WebDAV. Failing to find a working example, I studied the comments in the source and wrote one myself. jsDAV is a port from a PHP library. The Sabre manual is useful guide in general. One thing to remember is that since we're in an asynchronous environment, functions that return the results in PHP might have to invoke a callback function instead. This usually happens when the operation in question involves reading from the disk. The first parameter to the callback will always be an error object, which should be null when all goes well.
'use strict';
var crypto = require('crypto');
var jsDAV = require("jsDAV/lib/jsdav");
var jsDAVLocksBackendFS = require("jsDAV/lib/DAV/plugins/locks/fs");
var jsDAVFile = require("jsDAV/lib/DAV/file");
var jsDAVCollection = require("jsDAV/lib/DAV/collection");
var jsExceptions = require("jsDAV/lib/shared/exceptions");
var VirtualFile = jsDAVFile.extend(
{
initialize: function(name, buffer) {
this.name = name;
this.buffer = buffer;
},
getName: function() {
return this.name;
},
get: function(callback) {
callback(null, this.buffer);
},
put: function(data, type, callback) {
callback(new jsExceptions.Forbidden("Permission denied to change data"));
},
getSize: function(callback) {
callback(null, this.buffer.length);
},
getETag: function(callback) {
var shasum = crypto.createHash('sha1');
shasum.update(this.buffer);
var etag = '"' + shasum.digest('hex') + '"';
callback(null, etag);
},
getContentType: function(callback) {
callback(null, 'text/plain');
}
});
var VirtualDirectory = jsDAVCollection.extend(
{
initialize: function(name, children) {
this.name = name;
this.children = children;
},
getChildren: function(callback) {
var list = [];
for (var name in this.children) {
list.push(this.children[name]);
}
callback(null, list);
},
getChild: function(name, callback) {
var child = this.children[name];
if (child) {
callback(null, child);
} else {
callback(new jsExceptions.NotFound("File not found"));
}
},
childExists: function(name, callback) {
var exists = (this.children[name] !== undefined);
callback(null, exists);
},
getName: function() {
return this.name;
}
});
var children = {};
for (var i = 1; i <= 10; i++) {
var name = 'file' + i + '.txt';
var text = 'Hello world, #' + i;
children[name] = VirtualFile.new(name, new Buffer(text, 'utf8'));
}
var grandchildren = {};
for (var i = 66; i <= 99; i++) {
var name = 'beer' + i + '.txt';
var text = i + ' bottles of beer';
grandchildren[name] = VirtualFile.new(name, new Buffer(text, 'utf8'));
}
children['folder'] = VirtualDirectory.new('folder', grandchildren);
var root = VirtualDirectory.new(null, children);
var options = {
node: root,
locksBackend: jsDAVLocksBackendFS.new(__dirname + "/data")
};
var port = 8000;
jsDAV.createServer(options, port);
It looks like jsDAV is the only option. It is a port of a PHP library and it is not setup in such a way that you can use it like a normal node.js module. I found a few examples of server types that others have created to connect it with dropbox and couchdb.
I am now working on a server type that will work more like you would expect a node.js module to work. The next step will be making it play nice with npm. You can see my fork here.