Visual Studio Javascript
Visual Studio Code supports many features for JavaScript and Node.js development. The features that ship with the downloaded product are the core features: debugging, IntelliSense, code navigation, etc. In addition, to these core features, you can install a large number of quality extensions to add features to VS Code for JavaScript development. Visual Studio 2019 includes improved support for the Vue.js framework, which improves the development experience when creating an application with Vue.js, JavaScript. Working with JavaScript IntelliSense #. Visual Studio Code's JavaScript IntelliSense provides intelligent code completion, parameter info. JavaScript projects (jsconfig.json) #. The presence of a jsconfig.json file in a directory indicates that the directory. Type checking JavaScript #. You can write and run unit tests in Visual Studio using some of the more popular JavaScript frameworks without the need to switch to a command prompt. Both Node.js and ASP.NET Core projects are. There are some extension in Visual Studio Code that is useful for web and app development using JavaScript, HTML, and CSS. This pack include extensions, git tools, todo list tools, recommended selection of themes and icons, and some utilities that useful in web development using JavaScript in front end stack or backend stack with Node JS.
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- Visual Studio Javascript And Html
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- Visual Studio Javascript Debug
JavaScript has evolved over the years. Today, JavaScript can run not only in browsers but also in Server, Desktop Application & IoT devices.
Visual Studio Code is a trendy code editor today. It is one of the best for JavaScript application development. Let’s see how to set up a simple JavaScript environment.
Requirements:
- Visual Studio Code
- Node.js
- NPM (it’s a package manager which comes with Node.js)
Let’s start with setup of JavaScript Environment.
Step 1: Install Node.js
Go to the node.js website by following the above link and click on the downloads section. Select the LTS version, which is a stable version of node.js.
According to your platform (Windows, Mac, or Linux) and bit (32 or 64), you can download node.js installer.
After download of the installer is completed, install Node.js on your computer.
Follow the next step to check whether it is installed correctly or not.
Step 2: Verify Installation of Node.js and NPM
Drivers vex robotics usb devices. Go to command prompt.
Type node -v command and press Enter. You should get a node.js version.
Next,
Type npm -v command and press Enter. You should get a NPM version.
It should look like below.
If you get the proper versions means Node.js and NPM are rightly installed.
Step 3: Install Visual Studio Code
Follow the above link to the Visual Studio Code website and download setup according to your platform.
After downloading, install the Visual Studio Code to your computer.
Open it as an administrator.
It will look like this.
Step 4: Create and Open Folder
Create a folder on your computer at C or D drive. Keep the folder name in a small case. For example, jsexample.
Inside Visual Studio Code, go to the Fileand Click on Open Folder.
Select the folder which you have created. After selecting, you will get a folder inside VS Code Explorer.
Now go to the terminal in the menu and click on New Terminal. It will open terminal with the path in which you have created the folder.
Step 5: Create index.html File
In the folder, create an index.html file. You can create it from explorer where you can find the option to add a new file or directly create inside the folder location (Make sure it appears inside VS Code Explorer).
Add below sample code in index.html file and Save.
Step 6: Project Initialization
It is essential to initialize the project. You need to use NPM Command, which will create required files inside the folder.
In the terminal window type below command and hit enter.
It will automatically create the package.json file inside the folder.
Step 7: Install Lite Server
The lite server we will be using to host the application locally.
Use the following command in the terminal to install the lite server in the project and hit enter.
It will create a node_modules folder and package-lock.json inside the project. node_modules will contain required dependency for lite-server.
Below, files and folder should be part of your project till now.
Step 8: Modify package.json File
To start lite-server, you need to make small changes in the package.json file. Modify script object and change it’s ‘start’ property value to lite-server.
Visual Studio Javascript Console
It should look like this.
Step 9: Start the Website with Light Server
Finally, we have come to the last step.
Go to the Terminal and type below command and hit Enter.
Lite-Server will automatically start a locally hosted website in the browser. You should get the below result if everything above is correctly setup.
To stop lite-server, you need to press ctrl + c in the terminal. It will ask you the below question.
Terminate batch job (Y/N)?
Type Y and hit enter. It will stop the server.
That’s it. It is effortless to set up a primary JavaScript environment by following the above steps.
-->JavaScript is a first-class language in Visual Studio. You can use most or all of the standard editing aids (code snippets, IntelliSense, and so on) when you write JavaScript code in the Visual Studio IDE. You can write JavaScript code for many application types and services.
Note
We have joined the community-wide effort to make MDN web docs the web's one-stop, premiere development resource, by redirecting all (500+ pages) of Microsoft's JavaScript API reference from docs.microsoft.com to their MDN counterparts. For details, see this announcement.
Support for ECMAScript 2015 (ES6) and beyond
Visual Studio now supports syntax for ECMAScript language updates such as ECMAScript 2015/2016.
What is ECMAScript 2015?
JavaScript is still evolving as a programming language and TC39 is the committee responsible for making updates.ECMAScript 2015 is an update to the JavaScript language that brings helpful new syntax and functionality. For a deep dive on ES6 features, check out this reference site.
In addition to support for ECMAScript 2015, Visual Studio also supports ECMAScript 2016 and will have support for future versions of ECMAScript as they are released. To keep up with TC39 and the latest changes in ECMAScript, follow their work on GitHub.
Transpile JavaScript
A common problem with JavaScript is that you want to use the latest ES6+ language features because they help you be more productive, but your runtime environments (often browsers) don't yet support these new features. This means that you either have to keep track of which browsers support what features (which can be tedious), or you need a way to convert your ES6+ code into a version that your target runtimes understand (usually ES5). Converting your code to a version that the runtime understands is commonly referred to as 'transpiling'.
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One of the key features of TypeScript is the ability transpile ES6+ code to ES5 or ES3 so that you can write the code that makes you most productive, but still run your code on any platform. Because JavaScript in Visual Studio 2017 uses the same language service as TypeScript, it too can take advantage of ES6+ to ES5 transpilation.
Before transpilation can be set up, some understanding of the configuration options is required.TypeScript is configured via a tsconfig.json
file.In the absence of such a file, some default values are used.For compatibility reasons, these defaults are different in a context where only JavaScript files (and optionally .d.ts
files) are present.To compile JavaScript files, a tsconfig.json
file must be added, and some of these options must be set explicitly.
The required settings for the tsconfig file are as follows:
allowJs
: This value must be set totrue
for JavaScript files to be recognized. The default value isfalse
, because TypeScript compiles to JavaScript, and the compiler should not include files it just compiled.outDir
: This value should be set to a location not included in the project, in order that the emitted JavaScript files are not detected and then included in the project (seeexclude
).module
: If using modules, this setting tells the compiler which module format the emitted code should use (for examplecommonjs
for Node, or bundlers such as Browserify).exclude
: This setting states which folders not to include in the project.The output location, as well as non-project folders such asnode_modules
ortemp
, should be added to this setting.enableAutoDiscovery
: This setting enables the automatic detection and download of definition files as outlined previously.compileOnSave
: This setting tells the compiler if it should recompile any time a source file is saved in Visual Studio.typeAcquisition
: This set of settings control the behavior of automatic type acquisition (further explain in this section)
Marantz driver download. In order to convert JavaScript files to CommonJS modules and place them in an ./out
folder, you could use the following tsconfig.json
file:
With the settings in place, if a source file (./app.js
) existed and contained several ECMAScript 2015 language features as follows:
Then a file would be emitted to ./out/app.js
targeting ECMAScript 5 (the default) that looks something like the following:
Visual Studio Javascript And Html
Better IntelliSense
JavaScript IntelliSense in Visual Studio 2017 will now display a lot more information on parameters and member lists. This new information is provided by the TypeScript language service, which uses static analysis behind the scenes to better understand your code. You can read more about the new IntelliSense experience and how it works here.
JSX syntax support
JavaScript in Visual Studio 2017 has rich support for the JSX syntax. JSX is a syntax set that allows HTML tags within JavaScript files.
The following illustration shows a React component defined in the comps.tsx
TypeScript file, and then this component being used from the app.jsx
file, complete with IntelliSense for completions and documentation within the JSX expressions.You don't need TypeScript here, this specific example just happens to contain some TypeScript code as well.
Note
To convert the JSX syntax to React calls, the setting 'jsx': 'react'
must be added to the compilerOptions
in the tsconfig.json
file.
The JavaScript file created at `./out/app.js' upon build would contain the code:
Configure your JavaScript project
The language service is powered by static analysis, which means it analyzes your source code without actually executing it in order to return IntelliSense results and provide other editing features.Therefore, the larger the quantity and size of files that are included your project context, the more memory and CPU will be used during analysis.Because of this, there are a few default assumptions that are made about your project shape:
package.json
andbower.json
list dependencies used by your project and by default are included in Automatic Type Acquisition (ATA)- A top level
node_modules
folder contains library source code and its contents are excluded from the project context by default - Every other
.js
,.jsx
,.ts
, and.tsx
file is possibly one of your own source files and must be included in project context
In most cases, you will be able to just open your project and have great experience using the default project configuration. However, in projects that are large or have different folder structures, it may be desirable to further configure the language service to better focus only on your own source files.
Override defaults
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You can override the default configuration by adding a tsconfig.json
file to your project root.A tsconfig.json
has several different options that can manipulate your project context.A few of them are listed below, but for a full set of all options available, see the schema store.
Important tsconfig.json
options
Example project configuration
Given a project with the following setup:
- project's source files are in
wwwroot/js
- project's lib files are in
wwwroot/lib
bootstrap
,jquery
,jquery-validation
, andjquery-validation-unobtrusive
are listed in thebower.json
kendo-ui
has been manually added to the lib folder
You could use the following tsconfig.json
to make sure the language service only analyzes your source files in the js
folder, but still fetches and uses .d.ts
files for the libraries in your lib
folder.
Troubleshooting The JavaScript language service has been disabled for the following project(s)
When you open a JavaScript project that has a very large amount of content, you might get a message that reads 'The JavaScript language service has been disabled for the following project(s)'. The most common reason for having a very large amount of JavaScript source is due to including libraries with source code that exceeds a 20MB project limit.
A simple way to optimize your project is to add a tsconfig.json
file in your project root to let the language service know which files are safe to ignore. Use the sample below to exclude the most common directories where libraries are stored:
Add more directories as you see fit. Some other examples include 'vendor' or 'wwwroot/lib' directories.
Note
The compiler property disableSizeLimit
can be used as well to disable the 20MB check limit. Take special precautions when using this property because disabling the limit might crash the language service.
Notable Changes from Visual Studio 2015
As Visual Studio 2017 features a completely new language service, there are a few behaviors that will be different or absent from the previous experience.The most notable changes are the replacement of VSDoc with JSDoc, the removal of custom .intellisense.js
extensions, and limited IntelliSense for specific code patterns.
No more ///<references/>
or _references.js
Previously it was fairly complicated to understand at any given moment which files were in your IntelliSense scope. Sometimes it was desirable to have all your files in scope and other times it wasn't, and this led to complex configurations involving manual reference management. Going forward you no longer need to think about reference management and so you don't need triple slash references comments or _references.js
files.
See the JavaScript IntelliSense page for more info on how IntelliSense works.
VSDoc
XML documentation comments, sometimes referred to as VSDocs, could previously be used to decorate your source code with additional data that would be used to buff up IntelliSense results.VSDoc is no longer supported in favor of JSDoc which is easier to write and the accepted standard for JavaScript.
.intellisense.js
extensions
Previously, you could author IntelliSense extensions which would allow you to add custom completion results for third-party libraries.These extensions were fairly difficult to write and installing and referencing them was cumbersome, so going forward the new language service won't support these files.As an easier alternative, you can write a TypeScript definition file to provide the same IntelliSense benefits as the old .intellisense.js
extensions.You can learn more about declaration (.d.ts
) file authoring here.
Unsupported patterns
Visual Studio Javascript Debug
Because the new language service is powered by static analysis rather than an execution engine (read this issue for information of the differences), there are a few JavaScript patterns that no longer can be detected.The most common pattern is the 'expando' pattern.Currently the language service cannot provide IntelliSense on objects that have properties tacked on after declaration.For example:
You can get around this by declaring the properties during object creation:
You can also add a JSDoc comment as follows: