Common Usage Revealed: Mastering JS Built-in Objects

To master the common usage of JS built-in objects, specific code examples are required

When developing using JavaScript, we often deal with various built-in objects. These built-in objects provide a wealth of functions and methods that can help us implement various complex logic and operations. Learning to master the common usage of these built-in objects can improve our coding efficiency and development quality. This article will introduce several common JS built-in objects and give specific code examples.

1. Math object

The Math object provides many mathematics-related methods, such as logarithms, trigonometric functions, exponential operations, etc. Here are some commonly used sample codes:

// 获取一个随机数
let randomNum = Math.random();
console.log(randomNum);

// 求绝对值
let absNum = Math.abs(-10);
console.log(absNum);

// 求平方根
let sqrtNum = Math.sqrt(16);
console.log(sqrtNum);

// 求最大值
let maxNum = Math.max(1, 2, 3);
console.log(maxNum);

// 求最小值
let minNum = Math.min(1, 2, 3);
console.log(minNum);

2. Date Object

The Date object is used to handle dates and times. It provides many methods, such as getting the current time, setting the time, formatting output, etc. Here are a few commonly used code examples:

// 获取当前时间
let currentDate = new Date();
console.log(currentDate);

// 获取年份
let year = currentDate.getFullYear();
console.log(year);

// 获取月份（从0开始计数，0代表一月）
let month = currentDate.getMonth();
console.log(month);

// 获取日期
let day = currentDate.getDate();
console.log(day);

// 设置日期
currentDate.setDate(10);
console.log(currentDate);

// 格式化输出日期
let formattedDate = currentDate.toLocaleDateString();
console.log(formattedDate);

3. String object

String object is used to process strings. It provides many methods, such as getting the string length, finding substrings, replacing strings, etc. Here are a few commonly used code examples:

// 获取字符串长度
let str = "Hello, world!";
let length = str.length;
console.log(length);

// 查找子串
let index = str.indexOf("world");
console.log(index);

// 替换字符串
let newStr = str.replace("world", "JavaScript");
console.log(newStr);

// 字符串分割
let splittedStr = str.split(",");
console.log(splittedStr);

4. Array object

The Array object is used to process arrays. It provides many methods, such as adding elements, deleting elements, traversing arrays, etc. The following are several commonly used code examples:

// 创建一个空数组
let arr = [];

// 添加元素
arr.push(1);
arr.push(2);
arr.push(3);
console.log(arr);

// 删除元素
arr.pop();
console.log(arr);

// 数组遍历
arr.forEach(function(element) {
    console.log(element);
});

The above is only a brief introduction and sample code for several common built-in objects. In actual development, there are many other built-in objects available for use, such as RegExp objects, JSON objects, etc. Through continuous learning and practice, we can master the usage of these built-in objects more deeply and improve our programming level.

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