Welcome to the third part of a six-part series on building a web page calculator. In the previous part I gave you the skeletons of our two standard calculator functions. But there are fine details to these functions that we have to examine and appreciate. We start with the showNum() function.
This is not a case for the switch statement. From the explanation of all the code I have given above, we see that there can be one leading zero for the number on the display when there is no decimal point. I decided that any such leading zero should be removed. This is the behavior of physical calculators.
This code segment removes the leading zero. It first of all copies the content of the display to the strToTest local variable. It then uses a regular expression to see if there is a leading zero. If there is, it removes it from the value of the strToTest variable. Then it copies the result back to the display.
We have done enough for this part of the series. We continue in the next part.
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Coding a Web Page Calculator
