how does javascript's closure work if we want to preserve a value in currying

Question

I have written the code

// Handlers
function successHandlerFactory (savedFlag) {

  return function (res, savedFlag){
    if (res.data && res.status == 200) {
      ngcoupon_offerManager.addOffers(res.data.offers, -1, savedFlag);
      console.log('offers response', res, 'savedFlag', savedFlag);
    } else {
      console.error('something is wrong to get offers', res);
    }
  }
};

var offerSuccessHandler = function() {
    return successHandlerFactory();
}();
var savedofferSuccessHandler = function () {
  return successHandlerFactory(true);
}();

but apparently its giving out savedFlag undefined every executinon I make.

How come this does not work

Have you already looked at [How do JavaScript closures work?](http://stackoverflow.com/questions/111102/how-do-javascript-closures-work?rq=1)? — PM 77-1, Jul 15 '14 at 23:09
Change `return function (res, savedFlag){` to `return function (res){`. — Derek 朕會功夫, Jul 15 '14 at 23:11
Why not `var offerSuccessHandler = successHandlerFactory()` instead of the IIFE? — RobG, Jul 15 '14 at 23:22

score 5 · Accepted Answer · answered Jul 15 '14 at 23:11

The issue is in this part of the code:

function successHandlerFactory (savedFlag) {
  return function (res, savedFlag){
    ...

You're re-declaring savedFlag in the inner function, which ends up being the variable that is captured in the success handler. Try simply removing the second parameter of the returned function.

how does javascript's closure work if we want to preserve a value in currying

1 Answers1