摘要：
function flipCoin(): "heads" | "tails" { if (Math.random() > 0.5) return "heads" return "tails" } function maybeGetUserInfo(): | ["error", Error] | [" 阅读全文
摘要：
1. const values = [3, "14", [21]] for (let a in values) { // ^? } for (let b of values) { // ^? } . . . . Answer: for...in loop: The for...in statemen 阅读全文