In this version of application we have now object,in witch we store initial value as property.
calc.lastResult;all a standalone function we have ,now is part of object and became a methods in a calc object.as you see in fallowing example.
var calc = {
lastResult: 0000,
operate:function(operation,arg1,arg2){
if(arg2){
return operation(arg1,arg2);
}else{
return operation(arg1,lastResult);
}
},
add:function(arg1,arg2){
return arg1 + arg2;
},
subtract: function(arg1,arg2){
return arg1 - arg2;
},
multiply: function(arg1,arg2){
return arg1 * arg2;
},
divide:function(arg1,arg2){
return arg1 / arg2;
}
};method does what we would call addition, it's amazing peace of code,that takes two arguments (Numbers),in this case called arg1 and arg2 and returns sum of two arguments.
add:function(arg1, arg2) {
return arg1 + arg2;
};In next method description, we have subtraction action. It's takes two arguments (Numbers) and return very complicated value that comes from argument difrence.
subtract: function(arg1, arg2) {
return arg1 - arg2;
};We arrived to a method that takes two arguments (Numbers) and returns multiplication value.
multiply:function(arg1, arg2) {
return arg1 * arg2;
};And in final method we gone have two arguments (Numbers) and return division value.
divide: function(arg1, arg2) {
return arg1 / arg2;
};Method that can perform not only action with 3 arguments,but also can check or second argument exist,if exist it's perform operation function with two arguments profided,else for second argument it takes last returned value.
operate: function(operation, arg1, arg2) {
if (arg2) {
lastResult = operation(arg1, arg2);
return lastResult;
} else {
lastResult = operation(arg1, lastResult);
return lastResult;
}
};