Converting constants into JavaScript code

I've been diving into typescript recently and came across a simple code snippet that defines a constant variable and logs it to the console.

const versionNuber : number = 1.3;
console.log(versionNuber);

Upon running the tsc command on the file, I noticed that the generated javascript code looked like this:

var versionNuber = 1.3;
console.log(versionNuber);

This led me to wonder how I can transpile the constant correctly in javascript. Why doesn't tsc convert it properly even though constants are supported in javascript?

javascripttypescript

Answer №1

When it comes to the compiler options, one important setting is the target option. This option determines the version of the target language to which Typescript will be transpiled. By default, it is set to ES3, which was standardized in 1999 and is compatible with a wide range of environments.

If you wish to prevent const from being converted into var, you can change the target to ES2015 or a newer version. Before ES2015, const was not officially supported in JavaScript. Using it in older environments like IE10 (released in 2012) would result in errors.

You can check out this Playground link with ESNext target to see how const is preserved with the new target setting.

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