This example also shows that you can have a comment at the start of the line (i.e.Whenever a user is asked to provide input, the program should expect errors.If the user didn't type anything, but just clicked on the OK button, then the value stored in the variable would be "Diane".The two items are passed to the prompt() instruction inside the brackets, just as strings to be displayed on the screen are passed to document.write() inside the brackets. instruction takes two parameters: firstly, the message asking for the input, and then the default value. Compare the picture of the box above with the instruction.It is only after this that it encounters with a string following it.At this point, it takes the answer to the addition and concatenates it with the string containing . Well, this is the instruction you would use if you thought that the answer might be a decimal (non whole number) answer.The 'whole' is important in that - the "Int" part of the instruction stands for "integer", which is the technical name for a whole number. " I hear you say, "I thought that concatenating numbers with strings would turn the numbers into strings themselves.
The idea is that the user types the friend's name instead of this default value, and then click on OK.This is especially true if the program is long and complex, or if you want some other programmer to look at your code - you have to inform that person about any quirks of your program. The most common way of inserting a comment into a program is by using two forward slashes, //, together (no spaces between them).Anything following that on the same line is ignored until the end of the line is reached. Here is an example of a comment: The words 'tax paid' and 'Calculate tax paid' are ignored by the program.The space after the comma is optional - I put it in because it tends to make the instruction more readable.
will take a string, either as a constant inside quotation marks or a variable, or even as an expression, and will turn it into a whole number.
They are messages to any human looking at the Java Script code.