尝试将此功能包装在对象中

Question

Sorry for being vague and confusing everyone, Im grateful for all the feedback but let me explain what i am trying to do.

I want to create an object called Multiplier with two methods: multiply and getCurrentValue multiply should initially return the number supplied * 1 and from then on whatever the current value is times the number supplied, getCurrentValue should return the last answer returned from multiply.

Hey everyone I am having a little trouble grasping this concept.

Here is my code so far:

var multiplier = {

    function multiply(){

    alert("Input a number to be multiplied by 1")

    var a = prompt("Input your desired number");

    var b = a * 1;

        return alert(b);

    }

}

multiply();

any help or further explaining on how i would go about this would be appreciated

Answer 1

var multiplier = {
    lastValue: null,

    getCurrentValue: function() {
        return lastValue;
    }, 

    multiply: function() {
        alert("Input a number to be multiplied by 1")
        var a = prompt("Input your desired number");
        var b = a * 1;
        lastValue = b;
        return alert(b);
    }
}

This should do what you want. You're defining an object named multiplier, that has two functions and a variable to save the last value.

Of course, there are other ways to accomplish this, but your question is a little vague.

A more object oriented approach would be like so.

function Multiplier() {
    var lastValue = null;
    this.getCurrentValue = function() {
        return lastValue;
    };

    this.multiply = function() {
        alert("Input a number to be multiplied by 1");
        var a = prompt("Input your desired number");
        var b = a * 1;
        lastValue = b;
        return alert(b);
    }
}

With this approach, your lastValue variable is private. You've only exposed the two functions. Now you can create a new one of these objects whenever you need one, like so.

var myMultiplier = new Multiplier();

And you can call functions on that multiplier like so.

myMultiplier.multiply();