如何反转`String.fromCodePoint`，即将字符串转换为代码点数组？

如何解决如何反转`String.fromCodePoint`，即将字符串转换为代码点数组？

String.fromCodePoint(...[127482,127480]) 给我一面美国国旗 (??)。

如何将标志转回 [127482,127480]？

解决方法

您正在寻找 codePointAt，也许使用传播（等）转换回数组，然后映射每个。

console.log(theString.codePointAt(0)); // 127482
console.log(theString.codePointAt(2)); // 127480
// Note −−−−−−−−−−−−−−−−−−−−−−−−−−^
// It's 2 because the first code point in the string occupies two code *units*

或

const array = [...theString].map(s => s.codePointAt(0));
console.log(array); // [127482,127480]

或通过 Sebastian Simon pointed out 及其映射回调跳过作为 Array.from 的临时步骤：

const array = Array.from(theString,s => s.codePointAt(0));
console.log(array); // [127482,127480]

示例：

const theString = String.fromCodePoint(...[127482,127480]);

console.log(theString.codePointAt(0)); // 127482
console.log(theString.codePointAt(2)); // 127480

const array = [...theString].map(s => s.codePointAt(0));
console.log(array);  // [127482,127480]

const array2 = Array.from(theString,s => s.codePointAt(0));
console.log(array2); // [127482,127480]

Spread 和 Array.from 都使用字符串 iterator 工作，它通过代码点工作，而不是像大多数字符串方法那样工作的代码单元。