5 ms·

It's to avoid using "new".

• aikah 12y ago
  > It's to avoid using "new". yeah,well one is still using new inside the constructor. it's pretty obvious to me that : 1/ one should read the docs before using an api 2/ capitalized functions are meant to be used as constructors. 3/ If you dont like this pattern,write builders and make them obvious. like Object.create() To me when i design js APIs, I have 2 kind of "templates" : the jQuery "$(o).after(b).get(0)"/underscore "_(object).method().value()" monadic api style that wraps types (like promises) OR The way the DOM is built,more java-ish with builders everywhere ( document.createElement ... ). So I hardly use new anymore. I get that people might make mistake or like Python style OO;but still, I think forcing the "new" in unecessary.
• iLoch 12y ago
  Cant you just "return this;" to avoid using "new"?
  • aikah 12y ago
    > Cant you just "return this;" to avoid using "new"? THIS will be the global scope if a function meant to be a constructor is called without new. Try that in your console function Foo(){this.foo = "bar";return this} then do : Foo() ; it will return window; so the answer is no.
    • greg5green 12y ago
      The answer is yes if you do: Foo.call({});
      • LazerBear 12y ago
        That's a cool trick, though 'instanceof' won't work in this case.
        • cygx 12y ago
          Yup. The proper way to emulate new is Foo.call(Object.create(Foo.prototype))
          • LazerBear 12y ago
            Douglas Crockford, is that you? Oh the lengths people will go to avoid using 'new'... I wonder if any linters out there warn when they see something like: something = SomeCapitalizedFunction() Because forgetting to use 'new' is really the only thing I could think of that makes this pattern dangerous.
            • jdlshore 12y ago
              Yes, jslint and jshint both do, by default, iirc. They'll also warn on the opposite (using 'new' with a function that doesn't start with an uppercase letter).
              • LazerBear 12y ago
                Ah that's fantastic, i've been using them for a while and never noticed.
• hderms 12y ago
  why do people want to avoid using new?
  • LazerBear 12y ago
    If you accidentally forget to use 'new' when you're supposed to, the "constructor" method will change the global object instead of a new object, it can cause strange behavior that is very hard to trace.
    • hderms 12y ago
      Ah, I see. I guess I've never forgotten to use new. That does sound incredibly annoying to debug.