In the start of my career , i was a web developer and i noticed that strong typed languages were dominant in market. I was impressed with new upcoming features in java script and python language. The idea of not declaring the variables made me more productive and i used to like my work. the first time i heard about Typescript the idea seemed like taking steps back to old days.
what changed my mind?
I had a strategy that, for individual projects I used simpler languages like java script but while working in a team or working on large scale I preferred using typescript. in this article i will try to explain the reason.
TYPESCRIPT
If you don’t have any know how of typescript i recommend to read the following overview:
https://www.tutorialspoint.com/typescript/typescript_overview.htm
and view the following: https://www.typescriptlang.org/docs/handbook/typescript-in-5-minutes.html
Comparison of Productivity and Maintenance
Typescript is an object oriented language used for app development. This means that the setup of project is remunerated with the maintenance of large scale projects. Lets see why it is so:
type safe= less errors
When we define the type in our code we allow the IDE to find out the errors and bugs while using the functions and classes that would be viewed by us at runtime.
Example:
function add (a: number , b: number):
number { return a+b;}
let mySum: number;
mySum=add(1,"two");
let myText: String;
myText=add(1,2);
I have used visual studio code and there is an error i.e “Two”
on line 4: error as string parameter is passed to a function that can only accept number
on line 6: error as assign to a string , the output gives a number .
these two errors would have gone unnoticed without typescript, showing bugs at runtime.
Project Modules exposed by IDE
There are hundreds of classes which are scattered across different files. When we declare types the IDE finds the origin files and relate the objects with them.
Programmers face difficulty in maintaining this language that is why they avoid transferring from java and C# to js but typescript helps in overcoming this obstacle.
Setting up express project with Typescript
lets see the steps taken to set up project in Express.js project :
npm init
install typescript package
npm install typescript -s
Typescript node package
Typescript cant be run in node.js engine rather it only runs java script. The node typescript package is used as transpiler for .ts files to .js scripts. Babel is used as typescript for trans-piling. however the market standard is to use Microsoft package for this purpose.
the script tsc is put inside the package.json :
“scripts”: {
“tsc”: “tsc”
},
This can be used to call typescript functions by using command line. below command is used:
npm run tsc — –init
this help in initializing the typescript by creating the file tsconfig.json . In this file we will remove comment i.e outDiroption and choose transpile location to deliever .js files :
Express.js installation
npm install express -s
As typescript dont know express class type so express and typescript are independent. A special npm package can be used to recognize express class:
npm install @types/express -s
HELLO WORLD
Below is an example:
https://expressjs.com/pt-br/starter/hello-world.html
var express=require( 'express' ) ;
var app = express();
app.get( '/'function (req,res){
res . send( 'Hello World! ' ) ;
});
app.1isten(3000, function ( )
{
console. log( ' Example app listening on port 3000! ')
});
now create folder app and inside it create file app.ts using following code:
// lib/app.ts
import express = require('express');
// Create a new express application instance
const app: express.Application = express();
app.get('/', function (req, res) {
res.send('Hello World!');
});
app.listen(3000, function () {
console.log('Example app listening on port 3000!');
});
COMPILATION OF FIRST APPLICATION
npm run tsc
this command creates a build folder and .js file:
Running EXPRESS
node build/app.js
on port 3000 we can see our output:
Transcript running by not using transpiling
Typescript can be run directly on the node by using the package of ts-node . it is used for development purpose . For final deployment or embedding use java script code. version .The ts-node is included as dependent component on another package, tts-node-dev. After the installation of ,ts-node-dev we should run commands to restart server whenever any change is made in original project files .
npm install ts-node-dev -s
some more scripts are added in package.json:
“scripts”: {
“tsc”: “tsc”,
“dev”: “ts-node-dev –respawn –transpileOnly ./app/app.ts”,
“prod”: “tsc && node ./build/app.js”
},
start dev environment :
npm run dev
run server :
npm run prod
