TypeScript target ES3

Question

Array.prototype.indexOf and Date.now have been introduced in ES5. Why doesn't Typescript transpile, if I compile following code stored in file test.ts?

Date.now();
[1,2,3].indexOf(2);

The command I use is tsc -t es3 test.ts. The resulting test.js is completely identical to test.ts.

Answer 1

Why doesn't Typescript transpile, if I compile following code stored in file test.ts?

• TypeScript doesn't polyfill.
• Use corejs to polyfill

More

• Lib option : https://basarat.gitbooks.io/typescript/content/docs/types/lib.d.ts.html#polyfill-for-old-javascript-engines