javascript - function example in text does not make sense to me -

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reading through eloquent javascript in attempt wrap head around functions, read example code:

function makeaddfunction(amount) {   function add(number) {     return number + amount;   }   return add; }  var addtwo = makeaddfunction(2); var addfive = makeaddfunction(5); show(addtwo(1) + addfive(1));

i gist of it, having examined code , read accompanying text several times on few hours, hasn't clicked me: exacly code doing? add function acquire number parameter? come show command? if so, how passed around? don't see it...

the function makeaddfunction takes number (amount) , returns function adds number passed in paramter number passed outer function. 

function makeaddfunction(amount) {    function add(number) {      return number + amount;    }      return add; }

calling var addtwo = makeaddfunction(2); equivalent writing following function:

   var addtwo = function(number) {      return number + 2;  // function returned makeaddfunction    }

you can call parameter addtwo(5);

here's fiddle: http://jsfiddle.net/eh4lk/1/ press run button execute


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