TypeScript 中的变量声明错误

Question

I know, TypeScript generate JavaScript file with equivalent code.

But, here is a problem, where TypeScript doesn't generate equivalent JavaScript code .

demo.ts

function foo()
{
    if(1)
    {
        let myName = "Raktim";
    }
    console.log(myName);
}
foo();

demo.js

function foo() {
    if (1) {
        var myName = "Raktim";
    }
    console.log(myName);
}
foo();

See above, I declared a locale variable myName in the demo.ts file. But, look the JavaScript code it declare myName variable as global variable.

Summary: TypeScript generated JavaScript code's variable always are in global scope (in my case).

So, end of the code the meaning is changed. Why?

Answer 1

i think you are using something like webpack that use babel to transpile code.

https://babeljs.io/docs/en/babel-preset-env

you need to tell babel your target browser.

ex if you target the last chrome that read let and const the compiled code doesn't change

UPDATE: solved in comment using --target options ex: tsc --target ES2016 file.ts