js indexof 大小写

str.indexOf(searchValue[, fromIndex])

let str = "Hello World";
console.log(str.indexOf("hello")); // 输出: -1
console.log(str.indexOf("Hello")); // 输出: 0

let str = "Hello World";
let searchValue = "hello";

let lowerCaseStr = str.toLowerCase();
let lowerCaseSearchValue = searchValue.toLowerCase();

console.log(lowerCaseStr.indexOf(lowerCaseSearchValue)); // 输出: 0

function indexOfIgnoreCase(str, searchValue) {
  return str.toLowerCase().indexOf(searchValue.toLowerCase());
}

let str = "Hello World";
let searchValue = "hello";

console.log(indexOfIgnoreCase(str, searchValue)); // 输出: 0