当我尝试使用IFFE时，为什么这段代码不起作用？

Question

I tried to run this code.

var temp = (function () {
var a =10;
return {
    function (a) {
        console.log('Value of a is ' + a);
    }
 }
})();
temp();

I expect IIFE to return the function and assign it to the temp variable, but instead, I get the error below.

Uncaught TypeError: temp is not a function

Whats wrong with that?

Answer 1

You are returning a block inside which a function is defined. Instead return the function directly. Please find the below code for reference.

   var temp = (function () {
   var a =10;
   return function (a) {
      console.log('Value of a is ' + a);
      }
   })();
   temp();

And if you want to access the value of 'a' from the outer scope then use a different name for the parameter in the inner function.

   var temp = (function () {
   var a =10;
   return function (b) {
      a = b || a;
      console.log('Value of a is ' + a);
      }
   })();
   temp();

Answer 2

You need to remove the object literals from the return & return a named function

 var temp = (function() { var a = 10; return function test(a) { console.log('Value of a is ' + a); } })(); temp(); 

Answer 3

I guess you got confused with '{}' instead of '()'.

var temp = (function () {
var a =10;
return (
    function (a) {
        console.log('Value of a is ' + a);
    }
 )
})();
temp(<pass 'a' here>);

Further you are returning a function definition, which is not bound to 'a'. Try calling 'temp' with an argument.