Identifiers are expanded to their string value if the identifier is the name of a defined variable; otherwise, they are used literally. They are also used literally if they are surrounded by double quotes. For example:
s = abc // same as s = "abc" if abc is not defined
..or..
abc = Hello s = abc // same as s = "Hello" (if Hello is not defined!) s = "abc" // s equals "abc"
To avoid unintentionally using the name of variable as its value, you should get into the habit of declaring your variables with the var statement.