Learning JavaScript

Appendix A. Answers

Chapter 2

1. The following are valid:

2. $someVariable
   _someVariable
   some_variable
   somèvariable

3. The function variable uses a reserved JavaScript keyword, someVariable and 1Variable both start with invalid characters, and some*variable uses an invalid character, a JavaScript operator (*), as part of the variable name. All invalid names generate JavaScript errors.

4. The identifiers are converted as follows:

5. The variable some-month becomes someMonth, using CamelCase notation.

6. The function theMonth becomes getTheCurrentMonth, using relevant verbs and other distinguishing information.

7. The const current-month becomes CURRENT-MONTH, using constant-width uppercase letters.

8. The variable summer-month becomes summerMonths, maintaining consistency between the array of items and variable name.

9. The MyLibrary-afunction function becomes mylibraryFunctionverbFunctionname.

10. Important point to remember: conjugation is the bane of coders. Use a backslash before the inner single quote so that it’s interpreted literally, and not end-of-string:

11. var someString = ‘Who once said, “Only two things are infinite, the universe and human stupidity, and I\’m not sure about the former.”’;

12. The following code would work:

13. var fltNumber = 432.54;
    var intNumber = parseInt(fltNumber);
    var octNumber = parseInt(intNumber,2);
    var hexNumber = parseInt(intNumber,16);

14. The function parseInt returns the decimal base integer of the floating-point number, which is 432. It can also take a second parameter, specifying ...