Making function parameters required
Regular JavaScript has no concept of required parameters. We can use default parameter values to emulate this feature.
JavaScript
Read fire tipPrefixes like “is”, “has”, or “does” help emphasize that a variable holds a Boolean value.
if (monday) {
// `monday` could be the date of next Monday. You wouldn’t expect this to
// be `true` or `false`.
}
if (isMonday) {
// This reads like the question “is Monday?”, which you would answer with
// “yes” or “no”. The name tells you that this has to be Boolean.
}
if (children) {
// `children` could be a list of names or whether a person has children or
// not. It’s difficult to tell if this is an array or a Boolean.
}
if (hasChildren) {
// You can only read this as “has children?”, which is either `true` or
// `false`. Ideally.
}
if (rocks) {
// Could be the name of your favorite rocks, like “The” or “30”.
}
if (doesRock) {
// This does rock, `true`. Note how it’s not called `doesRocks`, which
// would read a little awkward.
}
Regular JavaScript has no concept of required parameters. We can use default parameter values to emulate this feature.