1 Reply Latest reply on Jul 3, 2017 4:16 PM by try67

    Newbie Question

    Gutterfish Adobe Community Professional


      So even though this question doesn't pertain to Acrobat I'm asking it here because it's a javaScript question.

      I have a little scripting experience but I'm brand new to JavaScript.


      Can someone please explain the example of the ++ operator found on this page?

      The example is below so you don't actually need to follow the link.

      Arithmetic operators - JavaScript | MDN


      // Postfix

      var x = 3;

      y = x++; // y = 3, x = 4


      // Prefix

      var a = 2;

      b = ++a; // a = 3, b = 3


      A little history...

      I was trying to increment a variable by one through each iteration of a conditional statement.

      I was trying to duplicate an item "x" number of times until "x" equaled 10.

      I basically wrote the offending line of code as     x = x++;

      That statement sent the script into an infinite loop.

      I did this based on my experience with MEL for Maya.


      So from what I read & what was explained to me about JavaScript

      I learned that unlike the other language I know

      a postfix ++ operator would keep the variable the same &

      a prefix ++ operator would increment it by one.

      However in the above example I am confused by two things:


      first: the inclusion of the second variable "b"

      second:  In both the postfix & prefix examples "x" gets incremented by one


      If postfix is supposed keep the value the same & prefix is supposed to add 1, then why do both examples add 1?


      For bonus points & if it's not too much trouble....

      Pertaining the postfix operator keeping the same value....

      Why might I want to add an operator to a variable that does nothing? (keeps it the same)


      Thanks for taking the time to read this & I appreciate any help.