<\/p>\n
var doSomething = function(paramOne, paramTwo, fn) {\n paramOne = paramOne * 8;\n \/\/ return the result of calling this function\n return fn(paramOne, paramTwo);\n};\n\nfunction sum(paramOne, paramTwo) {\n \/\/ add the passed in arguments and return the value\n return paramOne + paramTwo;\n}\n\n\/\/ set one\n\/\/ argument 3 is a reference to the predefined function\n\/\/ with the name \"sum\"\nvar foo = doSomething(2, 2, sum);\n\/\/ if that function didnt already exist we could define\n\/\/ and inject it directly into doSomething when we call it\n\/\/ So the beneath would be exactly equivalent because the \n\/\/ function you define on the spot is the same as the \n\/\/ predefined sum function\nvar bar = doSomething(2, 2, function(paramOne, paramTwo) {\n return paramOne + paramTwo;\n});\n\/\/ and thats all we are doing in set two\n\n\/\/ if we consider primitive variables the concept is the same\n\/\/ we can have variable x containing value 5\nvar x = 5;\n\/\/ then alert it\nalert(x);\n\/\/ here variable x and its value are predined but if it wasnt\n\/\/ we could simply insert it into the alert function as we call it\nalert (5);\n\/\/ no need for a predefined variable just like no need for a\n\/\/ predefined function in set two \n\n\/\/ set two\nvar bar = doSomething(3, 4, function(paramOne, paramTwo) {\n return paramOne * paramTwo;\n});<\/pre>\n