indexOf() 方法查找字符串 a 在 arr数组中的位置(索引) const arr = ['a','b']; console.log(arr.indexOf('a')); // 0 1. 2. 3. 检查数组是否包含某个元素 includes()方法存在则返回true,反之为false。 indexOf()方法测试索引值不是 -1。 如果indexOf()不返回-1,则数组包含给定的元素。 1....
如果我们想从这个数组中删除任何重复的项目,我们可以使用filter()方法和indexOf()方法来检查任何给定的项目是否是重复的。 const filteredStrings = strings.filter((item, index) => { // Return to new array if the index of the current item is the same // as the first occurence of the item return...
A DisposableStack is an object that has several methods for keeping track of Disposable objects, and can be given functions for doing arbitrary clean-up work. We can also assign them to using variables because — get this — they’re also Disposable! So here’s how we could’ve written ...
The language service, along with TypeScript’s public API, uses a different set of allocators for certain objects. This allowed the TypeScript compiler to be a bit leaner, as data used only for the language service would never be used in the compiler. In TypeScript 5.5, the same mono...
To check if a string contains a substring in TypeScript, use the includes() method: const text = "TypeScript is awesome"; console.log(text.includes("awesome")); // true console.log(text.includes("Java")); // false This method is case-sensitive. For case-insensitive checks: ...
The TypeScript compiler includes several settings which affect core aspects of the language. Configure TypeScript usingtsconfig.jsonrather than command-line options. Turn onnoImplicitAnyunless you are transitioning a JavaScript project toTypeScript. ...
function sum(nums: number[]): number: Use ReadonlyArray if a function does not write to its parameters. interface Foo { new(): Foo; }: This defines a type of objects that are new-able. You probably want declare class Foo { constructor(); }. const Class: { new(): IClass; }: ...
suppressImplicitAnyIndexErrors(boolean) - Suppress--noImplicitAnyerrors for indexing objects lacking index signatures. noLib(boolean) - Don't include the default lib (with definitions for - Array, Date etc) lib(string[]) - List of library files to be included in the compilation. ...
suppressImplicitAnyIndexErrors (boolean) - Suppress --noImplicitAny errors for indexing objects lacking index signatures. noLib (boolean) - Don't include the default lib (with definitions for - Array, Date etc) lib (string[]) - List of library files to be included in the compilation. targe...
“Reading the documentation,” of course, means you get data-typed IntelliSense support and compile-time checking when using the objects that make up the library. It also lets TypeScript, under certain circumstances, infer the type of a variable from the context in which it’s used. Than...