如何在JavaScript中获取替换字符串

let str = "Hello World";
let newStr = str.replace("World", "JavaScript");
console.log(newStr); // 输出：Hello JavaScript

let str = "Hello World";
let newStr = str.replace(/o/g, "a");
console.log(newStr); // 输出：Hella Warld

let str = "Hello World";
let regex = /o/g;
let match = regex.exec(str);
while (match) {
  str = str.replace(match[0], "a");
  match = regex.exec(str);
}
console.log(str); // 输出：Hella Warld