Avoiding bad idioms and keeping an eye on the very bad parts

As with most C-based programming languages, it is best to avoid certain bad idioms that often cause code inefficiency and bugs.

Bad idioms

Here are a few bad idioms that should be identified as problematic:

• Declaring a variable at first use is a bad idea in JavaScript due to the fact that the developer will most likely give the variable global scope in order to access it later. It is better to organize the code from the start of the project and use intuitive and meaningful namespaces in order to organize the use of variables throughout the application.
• Using structures in a way that is not explicit or that was not originally intended should be avoided in all cases. For example, letting a switch statement fall through or assigning a value to a variable within the condition of a conditional statement are very bad idioms and should never be used.
• Relying on automatic semicolon insertion is a bad idea and can lead to code misinterpretation...