Phương thức charAt[] của đối tượng String trả về một chuỗi mới bao gồm đơn vị mã UTF-16 duy nhất nằm ở phần bù được chỉ định trong chuỗi
Thử nó
cú pháp
charAt[index]
Thông số
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
Một số nguyên giữa
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
Giá trị trả về
Một chuỗi đại diện cho ký tự [chính xác là một đơn vị mã UTF-16] tại
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
charAt[] trả về một chuỗi rỗngSự miêu tả
Các ký tự trong một chuỗi được lập chỉ mục từ trái sang phải. Chỉ mục của ký tự đầu tiên là
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
Nếu không cung cấp
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
charAt[], thì mặc định là const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
ví dụ
Hiển thị các ký tự ở các vị trí khác nhau trong một chuỗi
Ví dụ sau hiển thị các ký tự ở các vị trí khác nhau trong chuỗi "______44"
const anyString = "Brave new world";
console.log[`The character at index 0 is '${anyString.charAt[]}'`];
// No index was provided, used 0 as default
console.log[`The character at index 0 is '${anyString.charAt[0]}'`];
console.log[`The character at index 1 is '${anyString.charAt[1]}'`];
console.log[`The character at index 2 is '${anyString.charAt[2]}'`];
console.log[`The character at index 3 is '${anyString.charAt[3]}'`];
console.log[`The character at index 4 is '${anyString.charAt[4]}'`];
console.log[`The character at index 999 is '${anyString.charAt[999]}'`];
Những dòng này hiển thị như sau
The character at index 0 is 'B' The character at index 0 is 'B' The character at index 1 is 'r' The character at index 2 is 'a' The character at index 3 is 'v' The character at index 4 is 'e' The character at index 999 is ''
Nhận toàn bộ ký tự
Điều sau đây cung cấp một phương tiện để đảm bảo rằng việc đi qua một vòng lặp chuỗi luôn cung cấp toàn bộ ký tự, ngay cả khi chuỗi chứa các ký tự không có trong Mặt phẳng đa ngôn ngữ cơ bản
const str = "A\uD87E\uDC04Z"; // We could also use a non-BMP character directly
for [let i = 0; i