Typescript for (let i of someArray) doesn't work in IE11

Question

Does anyone know why, in TypeScript with a compilerOptions targeting ES6, I used the following syntax to iterate the array? It worked on both Edge and Chrome, but not IE11. It complained a; is missing on the beginning line of the for loop.

 for (let thisId of changedIDs) {... }

When I changed it to the plain old Javascript for loop, then it worked on all 3 browsers.

 for (var i = 0; i < changedAnswerIDs.length; i++) {... }

Answer 1

The issue is with the for...of loop. IE has limited support for ES6 syntax. As @Phix mentioned in the comment, you should change the compiler target to ES5 or earlier to support IE.

Answer 2

IE 11 doesn't fully support ES6. You can use Babel to compile to ES5. Babel: https://babeljs.io/ or any other compiler really. You can also use this link to see more about compatibility: http://kangax.github.io/compat-table/es6/