function in javascript... help me connect the dots -


i saw example in eloquent javascript , wondering how function works. please explain me?

function multiplier (factor) {     return function(number){        return number * factor;          };  }  var twice = multiplier(2);  console.log((twice(5));     // 10

i able follow parameter factor = 2.
im confused twice(5) , how becomes parameter number.

this example of 'closure' in javascript.

saying:

var twice = multiplier(2)

is same saying:

var twice = function(number){   return number * 2;  };

so twice becomes reference function give twice value send it.

the multiplier function returns function(number){...}, has 'closure' on factor (in case 2).

that's why when call twice(5), result of 10.

you'll want read on closures: https://developer.mozilla.org/en-us/docs/web/javascript/closures


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