The JavaScript exception "reduce of empty array with no initial value" occurs when a reduce function is used.

# Contributors by commit history https://github.com/mdn/content/commits/main/files/en-us/web/svg/reference/element/metadata/index.md # Original Wiki contributors Tigt a-mt fscholz mattwojo Sebastia...

The JavaScript exception "malformed URI sequence" occurs when URI encoding or decoding wasn't successful.

The JavaScript warning "unreachable code after return statement" occurs when using an expression after a return statement, or when using a semicolon-less return statement but including an expression directly after.

# Contributors by commit history https://github.com/mdn/content/commits/main/files/en-us/web/svg/reference/attribute/y2/index.md # Original Wiki contributors Jeremie 167

The then() method of Promise instances takes up to two arguments: callback functions for the fulfilled and rejected cases of the Promise. It stores the callbacks within the promise it is called on and immediately returns another Promise object, allowing you to chain calls to other promise methods.

The catch() method of Promise instances schedules a function to be called when the promise is rejected. It immediately returns another Promise object, allowing you to chain calls to other promise methods. It is a shortcut for then(undefined, onRejected).

The sticky accessor property of RegExp instances returns whether or not the y flag is used with this regular expression.

The Symbol.toPrimitive static data property represents the well-known symbol Symbol.toPrimitive. All type coercion algorithms look up this symbol on objects for the method that accepts a preferred type and returns a primitive representation of the object, before falling back to using the object's valueOf() and toString() methods.

The find() method of Array instances returns the first element in the provided array that satisfies the provided testing function. If no values satisfy the testing function, undefined is returned.