sunhaoxiang

> Would you explain a bit more about:您能再多解释一下吗： > > ``` > P extends K? never : K extends P ? K : never > ``` > > I don't...

> @shx123qwe - happy to answer your question. I also put most of it in a [TS playground](https://www.typescriptlang.org/play/#code/PTAEAUCcHsAcFNIBcCeBpeLQBNrwM4B2A5EqPAB5LyHaj5KQCWhA5qAEbwDGAhgK754oABTQOANybRBAGxQBKUIWhles2RBgJk6TPlC9Iwhszb4AUCFGoEWuIlQYsAXnqMW7AD7L+AWy5IUB98FADoWQAaQ1pfAMQDXljQ8NlE4xIyU098BQtbYSgHXWcAUSoabHwAZQ82UDcinSdMcgraA2z6gH5QRn5hAC5QADN1IQBuUFArMAL7Zr0UcuoO2rN2NzG0+AmLWdAAWmOT07Pzi8ur65vb84OAFWhQWBhsfm5hXj6UO1UAC0QfX+SVG43g0QA7sJCPB4HQkM8-LwANbCJCA0DcaC0JhIaSEdSgABU2CY2Q4-HxEngxIAdLMDgAleB+VmBYG8MjY3H4nFEgrpYRkilUpg00A4+SgJgjYHCABE3EB3DRCN+8AVM2sIjZSU88p+dlePHhBoxwgABpRVlVLaA0ShIdBINglOTDKBWDREExuEb4HTtcADgB1YR8QigQRfehMPywWTCb2w5j++YKlaVfBaxFe+BkEUeSnUvEoQb5DWgLMdAA8D2iAFUAHwNUAPNq2gyN0C9fpDME7PbzJqOJY1qrrTwAEXJxbFErcE-wtdHJUw0S6rGbU2DAYWY7K7UndVYs9F1OEbg40Ai8CSewOAE0ZKA-ExWP8yM7aEDIf8sGhL1VFAS0bzvJJ7SSOgVDIS1+0tBlrAASSQYgDC4PgY09ItmBLcUIxxMk+UJTRXmgd5PkSaNCAJSU5UFYYDhxYQRhdcheGVLEcQYPEBkIMhoAYzElRVNUtX4WicQDBkDmqZ4LX3cjKPhTgsGXVdtEPDd3A2VsPXgyABmCQchBM7YhHtQ5W0M4yfAs+ArJs8Ck0giw9zuTyvO8nyrn2awnjfVF0X+D18H4HQsVcoIgMjUBIWYahPRpSB8DooTQOXe0MS5F43g+Ag92+IsWG4LJT1AWQ8UQIk2KCe8uJ5XikH4wThMVZUeHEgMK3mKc2FlFB61bNwOxtbNdINXp0NPYhQGGMbjwMQh-A5aaVviSA5oWzsJpSG9NGm-aIm20B0OgNlJQtIICmIYcq2qf5oEhc950vDSG1AFs20Wrsvt7UCABIAG9+tYQbhoAXyOVsEPmoHQdPCGHmbaHrNMxzHz6p7ITXFpliWsG20e57Xrwhd4A0vGlk3U8dwObHnupo8uyJtwFS3GG+iMzUTIVDaOXRhytR8DmwgOrnhf2Rnca09cCa7AA5VagTcEmXrncn3qWzTinx6IBcQenrBl5nMGXZXNrbMXUkl8ERdADmKqF+2+cNoJ0f7BV-LmQFjHQ5QAQNfAEG4JgiV4G8qQPeXog4LBFMhXhy0rOx1YAQVgv3GykqM1ZxsmmHwmkNM5kJxYiEyJGgJhsFpvS9hNh6cczgFEBzuj2c5z2eYdm2JZdnY+-wC7hDbm6q0HoRvceULEjSZ4mA0QRGC5Qqcu-QEo2+HliIJAUqw9XCi4p6JFNErr4VzKtjtkBngoMaTFNJTWT+obBiVACR1GM2VgH-GgMoyAehjHQWQa8ggsENLvPE+9NDzEoCafAaUcR0iAA)- 很高兴回答你的问题。我还将其大部分放在 TS Playground 中 > > `PropertyKey` doesn't extend `string` because (obviously)...

> @shx123qwe - happy to answer your question. I also put most of it in a [TS playground](https://www.typescriptlang.org/play/#code/PTAEAUCcHsAcFNIBcCeBpeLQBNrwM4B2A5EqPAB5LyHaj5KQCWhA5qAEbwDGAhgK754oABTQOANybRBAGxQBKUIWhles2RBgJk6TPlC9Iwhszb4AUCFGoEWuIlQYsAXnqMW7AD7L+AWy5IUB98FADoWQAaQ1pfAMQDXljQ8NlE4xIyU098BQtbYSgHXWcAUSoabHwAZQ82UDcinSdMcgraA2z6gH5QRn5hAC5QADN1IQBuUFArMAL7Zr0UcuoO2rN2NzG0+AmLWdAAWmOT07Pzi8ur65vb84OAFWhQWBhsfm5hXj6UO1UAC0QfX+SVG43g0QA7sJCPB4HQkM8-LwANbCJCA0DcaC0JhIaSEdSgABU2CY2Q4-HxEngxIAdLMDgAleB+VmBYG8MjY3H4nFEgrpYRkilUpg00A4+SgJgjYHCABE3EB3DRCN+8AVM2sIjZSU88p+dlePHhBoxwgABpRVlVLaA0ShIdBINglOTDKBWDREExuEb4HTtcADgB1YR8QigQRfehMPywWTCb2w5j++YKlaVfBaxFe+BkEUeSnUvEoQb5DWgLMdAA8D2iAFUAHwNUAPNq2gyN0C9fpDME7PbzJqOJY1qrrTwAEXJxbFErcE-wtdHJUw0S6rGbU2DAYWY7K7UndVYs9F1OEbg40Ai8CSewOAE0ZKA-ExWP8yM7aEDIf8sGhL1VFAS0bzvJJ7SSOgVDIS1+0tBlrAASSQYgDC4PgY09ItmBLcUIxxMk+UJTRXmgd5PkSaNCAJSU5UFYYDhxYQRhdcheGVLEcQYPEBkIMhoAYzElRVNUtX4WicQDBkDmqZ4LX3cjKPhTgsGXVdtEPDd3A2VsPXgyABmCQchBM7YhHtQ5W0M4yfAs+ArJs8Ck0giw9zuTyvO8nyrn2awnjfVF0X+D18H4HQsVcoIgMjUBIWYahPRpSB8DooTQOXe0MS5F43g+Ag92+IsWG4LJT1AWQ8UQIk2KCe8uJ5XikH4wThMVZUeHEgMK3mKc2FlFB61bNwOxtbNdINXp0NPYhQGGMbjwMQh-A5aaVviSA5oWzsJpSG9NGm-aIm20B0OgNlJQtIICmIYcq2qf5oEhc950vDSG1AFs20Wrsvt7UCABIAG9+tYQbhoAXyOVsEPmoHQdPCGHmbaHrNMxzHz6p7ITXFpliWsG20e57Xrwhd4A0vGlk3U8dwObHnupo8uyJtwFS3GG+iMzUTIVDaOXRhytR8DmwgOrnhf2Rnca09cCa7AA5VagTcEmXrncn3qWzTinx6IBcQenrBl5nMGXZXNrbMXUkl8ERdADmKqF+2+cNoJ0f7BV-LmQFjHQ5QAQNfAEG4JgiV4G8qQPeXog4LBFMhXhy0rOx1YAQVgv3GykqM1ZxsmmHwmkNM5kJxYiEyJGgJhsFpvS9hNh6cczgFEBzuj2c5z2eYdm2JZdnY+-wC7hDbm6q0HoRvceULEjSZ4mA0QRGC5Qqcu-QEo2+HliIJAUqw9XCi4p6JFNErr4VzKtjtkBngoMaTFNJTWT+obBiVACR1GM2VgH-GgMoyAehjHQWQa8ggsENLvPE+9NDzEoCafAaUcR0iAA)- 很高兴回答你的问题。我还将其大部分放在 TS Playground 中 > > `PropertyKey` doesn't extend `string` because (obviously)...

> ```ts > // your answers > type Flatten = S extends [infer X, ...infer Y] ? > X extends any[] ? > Flatten : Flatten > : T >...

``` type KebabCase = S extends `${infer A}${infer Rest}` ? Rest extends Capitalize ? `${Lowercase}-${KebabCase}` : `${Lowercase}${KebabCase}` : ""; ``` why its wrong?

> ```ts > type KebabCase = S extends `${infer S1}${infer S2}` > ? S2 extends Uncapitalize > ? `${Uncapitalize}${KebabCase}` > : `${Uncapitalize}-${KebabCase}` > : S; > ``` the emphasis is...

> ```ts > type LengthOfString< > S extends string, > T extends string[] = [] > > = S extends `${infer F}${infer R}` > ? LengthOfString > : T['length']; >...