Angular successfully compiled without any issues despite the explicit cast of a number into a string variable

As I delve into the initial concepts of Angular, I have come across a puzzling situation. Here is the code snippet:

 import { Component } from '@angular/core';
 @Component({
 selector: 'sandbox',
 template: `
    <h1>Hello {{ name }}</h1>`
 })
 export class SanboxComponent {  
   name:string = "John Doe";  //name is declared as string
   constructor() {
     this.name = 34; //this should be the error..
   }
 }

Surprisingly, when I run this code on my browser, it still displays "Hello 34".

While I am familiar with JavaScript, TypeScript is relatively new to me. Based on my understanding, the designation 'name:string' implies that only a string value can be assigned. Can someone shed light on what might be happening here?

Answer №1

When using TypeScript, the transpiler will issue a warning by default, but it will still proceed with transpilation even if there are type errors present.

To ensure greater accuracy and prevent the transpiler from working with any type errors, you can make changes to your tsconfig.json file.

{
    "compilerOptions": {
        "noEmitOnError": true,
    }
}

Simply set the noEmitOnError option to true.

Answer №2

When your application is executed, it is transformed into JavaScript, which lacks type checking, allowing it to run smoothly without encountering errors. The strength of TypeScript lies in its strong typing system, where the integrated development environment (IDE) diligently tracks and notifies you of any type mismatches, such as assigning a number to a variable declared as a string. It is crucial to steer clear of using the any type, as it undermines the essence of TypeScript.

In essence, TypeScript is non-existent during runtime - only standard JavaScript is running, eliminating the potential for runtime errors :)

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