str.replace(regexp|substr, newSubstr|function)

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

let str = "The quick brown fox jumps over the lazy dog";
let newStr = str.replace(/the/gi, "a");
console.log(newStr); // "a quick brown fox jumps over a lazy dog"

let str = "Doe, John";
let newStr = str.replace(/(\w+), (\w+)/, "$2 $1");
console.log(newStr); // "John Doe"

let str = "The temperature is 25C today";
let newStr = str.replace(/(\d+)C/, function(match, p1) {
    return (parseInt(p1) * 9/5 + 32) + "F";
});
console.log(newStr); // "The temperature is 77F today"

let str = "apple orange apple";
// 错误方式 - 只替换第一个apple
str.replace("apple", "banana"); // "banana orange apple"

// 正确方式
str.replace(/apple/g, "banana"); // "banana orange banana"

let str = "1 + 1 = 2";
// 错误方式 - +在正则中有特殊含义
str.replace(/1 + 1/, "3"); // 不会匹配

// 正确方式1 - 转义
str.replace(/1 \+ 1/, "3"); // "3 = 2"

// 正确方式2 - 使用字符串替换
str.replace("1 + 1", "3"); // "3 = 2"

let str = "abc12345";
str.replace(/(\d+)/, function(match, p1, offset, string) {
    console.log(match); // "12345" - 完整匹配
    console.log(p1);    // "12345" - 第一个捕获组
    console.log(offset); // 3 - 匹配开始位置
    console.log(string); // "abc12345" - 原始字符串
    return "x";
});

let str = "Hello";
str.replace("H", "J");
console.log(str); // 仍然是 "Hello"

// 正确方式
let newStr = str.replace("H", "J");
console.log(newStr); // "Jello"

let str = "2023-05-15";
let newStr = str.replace(/(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/, "$<day>/$<month>/$<year>");
console.log(newStr); // "15/05/2023"

let str = "The numbers are 123, 456, and 789";
let newStr = str.replace(/\d+/g, function(match) {
    return parseInt(match) * 2;
});
console.log(newStr); // "The numbers are 246, 912, and 1578"

let html = "<div class='test'>Hello</div>";
let newHtml = html.replace(/<[^>]+>/g, "");
console.log(newHtml); // "Hello"