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JavaScript Tip: Throw an Error if a Required Parameter Is Missing
Michael Hoffmann
@mokkapps
Default function parameters allow named parameters to be initialized with default values if no value or undefined is passed.
We can use this approach to write a function that throws an error if a required parameter is missing:
index.js
const isRequired = () => {
throw new Error('Parameter is required!')
}
const foo = (bar = isRequired()) => {
console.log(bar)
}
foo() // throws the isRequired error
foo(undefined) // throws the isRequired error
foo(false) // logs "false"
foo(null) // logs "null"
foo('Test') // logs "true"