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> This means I can just write JavaScript and add comments for types. No transplier step, no messing around in a different but similar language, no additional co

• dtech 10y ago
  No. With flow you can do both: var x /*: string*/ = "" var x : string = "" With TS you can only do the latter. The first one has the advantage that it's legal Javascript, thus not requiring a compiler. Since typescript is set-up purely as a compiler anyway I'm not sure it would be a useful feature for them. A disadvantage could be that it's easier to make silent errors by making syntax errors in the comments. I don't how Flow would handle e.g. `var x /* number*/ = ""`
  • joshuacc 10y ago
    That's not entirely accurate. TypeScript 1.8 added the ability to use type information from JSDoc-style comments. For example: /** * @param {string} a * @param {number} b * @returns {string} */ function foo(a, b){ return a + b; } Is functionally identical to: function foo(a: string, b: number): string { return a + b; } See: https://github.com/Microsoft/TypeScript/issues/4790 https://github.com/Microsoft/TypeScript/issues/4790
    • Arnavion 10y ago
      Not equivalent - the TS compiler currently does not actually enforce the types in a JS file. See https://github.com/Microsoft/TypeScript/issues/4790#issuecomment-220807667 https://github.com/Microsoft/TypeScript/issues/4790#issuecom... The feature of parsing JSDoc comments is currently only used for providing completion info for JS editors and for consuming exported JS functions and variables in TS files.
      • joshuacc 10y ago
        Ah, you're right. Looks like I'd misunderstood the scope of that change.
    • abritinthebay 10y ago
      "functionally" identical to the type checker. But not functionally identical when it involves my fingers typing (the function there being my ergonomics). Flow would just be inline comments at the code points required.