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  1. #1
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    JavaScript Calculator: Parentheses

    I'm trying to program parentheses into my JavaScript calculator, but I'm having trouble doing it. What I've got is this:

    this.display = "(";

    where the variable, display, is what will be displayed in the calculator.

    Do you have any suggestions for me, or any source code I could look at? Thanks!

  2. #2
    SitePoint Evangelist
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    You are going to have to provide a bit more information.

    You have this.display but you talk about a variable display.

    A variable is declared by a var statement. for example

    var display;

    this.display is the display property of the this object. But what is "this"?

    How all this fits in with you calculator can only be speculated.

  3. #3
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    'this' is only the generic form of the variable, display. In earlier code in my calculator, I declared display as a variable: var display = 0;

    Display is initially set as 0 so the calculator starts with a blank screen.

    There are actually two variables in this calculator which I have declared: display and total. Both are declared in my code before the actual code I posted.
    var display = 0;
    var total = 0;
    When the user enters a number, this.display (the generic form) is assigned the value of that number. When an operand is hit (+, -, / ...), total is assigned the current value of display, and then display is reset to 0.

    Thank you very much for your help!

  4. #4
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    I apologize; I never answered what 'this' is. 'this' is the calculator object (if I understand your question properly. I'm very sorry; I'm a new programmer). The function I initially posted and every other function in the calculator is really a prototype function for the calculator object. So when I use this.display, I'm able to access the variable in any of my prototype functions.

    Please let me know if this didn't answer the question you asked. I feel like I hit the ball way into left field.


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