type StartsWith<T extends string, U extends string> = T extends `${U}${infer Last}` ? true : false;

Solution by ZhipengYang0605 #33110

// your answers
type StartsWith<T extends string, U extends string> = T extends `${U}${infer R}` ? true : false

Solution by pea-sys #32851

// 你的答案
type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true:false

Solution by shanguoteng #32815

type StartsWith<S1 extends string, S2 extends string> = S1 extends `${S2}${infer Rest}` ? true : false

type a = StartsWith<'abc', 'ac'> // expected to be false
type b = StartsWith<'abc', 'ab'> // expected to be true
type c = StartsWith<'abc', 'abcd'> // expected to be false

Solution by ZhulinskiiDanil #32712

type StartsWith<T extends string, U extends string> = T extends `${U}${infer _}` ? true : false

Solution by dev-hobin #32493

type StartsWith<T extends string, U extends string> = T extends `${U}${string}`? true:false

Solution by rkamely #32065

type StartsWith<T extends string, U extends string> = T extends `${U}${infer R}` ? true : false;

Solution by ricky-fn #31872

T extends `${U}${infer P}` ? true:false

Solution by Zhen-code #31801

type StartsWith<T extends string, U extends string> = T extends `${U}${infer T}`
  ? true
  : false;

Solution by vipulpathak113 #31632

// your answers
type last = string
type StartsWith<T extends string, U extends string> = T extends `${U}${last}`? true:false;

Solution by kangaroona #31149

// your answers
I think it's a little bit overdone

type IsMore<A, B> = A extends `${infer AF}${infer AR}` ? B extends `${infer BF}${infer BR}` ? IsMore<AR, BR> : true : false;

type _StartWith<T extends string, U extends String> =
  T extends `${infer TF}${infer TR}` ? U extends `${infer UF}${infer UR}` ?
  TF extends UF ? _StartWith<TR, UR> : false : true : true;

type StartsWith<T extends string, U extends string> = IsMore<U, T> extends true ? false : _StartWith<T, U>;

Solution by chenqy-yh #31080

type StartsWith<T extends string, U extends string> = 
  T extends `${infer F}${infer Rest}`? 
  U extends `${infer UF}${infer URest}` ?
  F extends UF ?
  StartsWith<Rest, URest> :
  false :
  true :
  U extends '' ? 
  true :
  false

Solution by gearonix #30881

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false;

Solution by kai-phan #30836

type StartsWith<T extends string, U extends string> = T extends `${U}${infer Rest}` ? true : false

Solution by maximallain #30555

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false;

Solution by kanishev #29854

复用已有的ReplaceAll

type StartWith<T extends string, E extends string> = T extends `${E}${infer R}` ? true : false;
type a1 = StartWith<"abcd", "abcd">;

Solution by sundial-dreams #29482

Solution:

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false;

Solution by DmitriiBr #29353

Cumbersome but, it is works

type StartsWith<T extends string, U extends string> = T extends `${infer L}${infer R}`
  ? U extends `${infer Lm}${infer Rm}`
    ? [Lm] extends [never]
      ? true
      : Lm extends L
      ? StartsWith<R, Rm>
      : false
    : true
  : T extends U
  ? true
  : false;

Solution by dmytro-shumak #29255

type StartsWith<T extends string, U extends string> = T extends ${U}${string} ? true : false;

Solution by DoubleWoodLin #28690

type First<T extends string> =  T extends `${infer F}${infer R}` ?  F : never;
type Rest<T extends string> = T extends `${infer F}${infer R}` ?  R : never;
type StartsWith<T extends string, U extends string> = U extends '' 
  ? true 
  : First<T> extends First<U> 
    ? First<T> extends never 
      ? false 
      : StartsWith<Rest<T>, Rest<U>> 
    ：false

Solution by breakinferno #28458

// your answers
type StartsWith<T extends string, U extends string> = T extends `${U}${infer R}` ? true : false;

Solution by GreattitJY #27657

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false

Solution by jjswifty #27624

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false;

Solution by jjswifty #27385

// your answers
type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false

Solution by daiki-skm #27305

type StartsWith<T extends string, U extends string> = T extends `${U}${infer O}` ? 
	true : false

Solution by 8471919 #27207

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false;

Solution by RainbowIsPerfect #26998

type StartsWith<T extends string, U extends string> = T extends `${U}${string}` ? true : false

Solution by smileboyi #26915

type StartsWith<T extends string, U extends string> = T extends `${U}${infer _}` ? true : false;

Solution by rldnd #26853

type StartsWith<T extends string, U extends string> = T extends `${U}${infer _}`
  ? true
  : false;

Solution by ryuji-1to #26817

type StartsWith<T extends string, U extends string> = T extends `${U}${infer R}`
  ? true
  : false;

Solution by ZhipengYang0605 #26633