There are many instances where we have to execute a function where we have no idea whether it actually exists or not. Let’s say for example, a function expects another function passed to it as parameter, which would later be executed as callback. A very common usage would be the callback function sent to AJAX…

Often, there are conditions where we need to provide a default value of a variable if it is undefined. As a case study, we will take up the situation, where we are passing a Boolean value to function and if the input is true, some action has to be taken. In case someone does not…