![]() The sleep function is pretty straightforward: async function sleep(millis) millis - how long to sleep in milliseconds Much better, isn't it? Before I get into the details of how fetchPage() and fetchUrls() work, let's first answer your question of how to wait before fetching the next page. For instance, this would be your main function: const urls = await fetchUrls(INITIAL_URL) I am a big fan of the async library and I've used for a long time. See example below.Delaying multiple page fetches with async/await In the meantime, the caller of the async function resumes execution. Non-thenable value: An already-fulfilled Promise is constructed and used.Įven when the used promise is already fulfilled, the async function's execution still pauses until the next tick.Thenable object (including non-native promises, polyfill, proxy, child class, etc.): A new promise is constructed with the native Promise() constructor by calling the object's then() method and passing in a handler that calls the resolve callback.Native Promise (which means expression belongs to Promise or a subclass, and nstructor = Promise): The promise is directly used and awaited natively, without calling then().The expression is resolved in the same way as Promise.resolve(): it's always converted to a native Promise and then awaited. Otherwise, if the rejected promise is not awaited or is immediately returned, the caller function will not appear in the stack trace. The function containing the await expression will appear in the stack trace of the error. If the promise is rejected, the await expression throws the rejected value. When execution resumes, the value of the await expression becomes that of the fulfilled promise. Using await pauses the execution of its surrounding async function until the promise is settled (that is, fulfilled or rejected). Warning: unreachable code after return statementĪwait is usually used to unwrap promises by passing a Promise as the expression.Warning: -file- is being assigned a //# sourceMappingURL, but already has one.TypeError: X.prototype.y called on incompatible type.TypeError: setting getter-only property "x".TypeError: Reduce of empty array with no initial value.TypeError: property "x" is non-configurable and can't be deleted.TypeError: invalid assignment to const "x".TypeError: invalid 'instanceof' operand 'x'.TypeError: cannot use 'in' operator to search for 'x' in 'y'.TypeError: can't redefine non-configurable property "x".TypeError: can't delete non-configurable array element.TypeError: can't define property "x": "obj" is not extensible.TypeError: can't convert BigInt to number.TypeError: can't assign to property "x" on "y": not an object.TypeError: "x" is not a non-null object.Synta圎rror: Using to indicate sourceURL pragmas is deprecated.Synta圎rror: unterminated string literal.Synta圎rror: unparenthesized unary expression can't appear on the left-hand side of '**'.Synta圎rror: unlabeled break must be inside loop or switch.Synta圎rror: Unexpected '#' used outside of class body.Synta圎rror: test for equality (=) mistyped as assignment (=)?.Synta圎rror: redeclaration of formal parameter "x".Synta圎rror: missing = in const declaration. ![]() Unicode character class escape: \p after property list.Character class escape: \d, \D, \w, \W, \s, \S.Enumerability and ownership of properties.
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