What are the built-in object types in js?

JavaScript is a scripting language widely used in web development. It has many built-in object types. These built-in object types provide various methods and properties for processing different data. Type and perform specific tasks. This article will introduce some common built-in object types of JavaScript and provide specific code examples.

1. Number object

The Number object is used to process numeric data types. It provides many useful methods and properties. For example, the toFixed() method is used to round a number to a string with a specified number of decimal places. The following is an example:

let num = 3.14159;
let fixedNum = num.toFixed(2);
console.log(fixedNum); // 输出3.14

2. String object

String object is used to process string data types. It also provides various methods and properties. For example, the toUpperCase() method is used to convert a string to uppercase. The following is an example:

let str = "hello world";
let upperStr = str.toUpperCase();
console.log(upperStr); // 输出HELLO WORLD

3. Array object

The Array object is used to process array data types. It provides many methods and properties for manipulating arrays. For example, the push() method is used to add one or more elements to the end of an array. The following is an example:

let arr = [1, 2, 3];
arr.push(4);
console.log(arr); // 输出[1, 2, 3, 4]

4. Object object

Object object is the most basic object type in JavaScript and the basis for all other object types. It provides many methods and properties for manipulating objects. For example, the keys() method is used to get all property names of an object. The following is an example:

let obj = {name: "John", age: 30};
let keys = Object.keys(obj);
console.log(keys); // 输出["name", "age"]

5. Date object

The Date object is used to process dates and times. It provides many methods and properties for getting and setting various parts of date and time. For example, the getDate() method is used to get the number of days in the current date. The following is an example:

let date = new Date();
let day = date.getDate();
console.log(day); // 输出当前日期的天数

6. Math object

The Math object is used to perform mathematical operations. It provides many methods and properties for working with numbers. For example, the sqrt() method is used to calculate the square root of a number. Here is an example:

let num = 16;
let sqrtNum = Math.sqrt(num);
console.log(sqrtNum); // 输出4

The above are just examples of some common built-in object types in JavaScript. In fact, JavaScript has many other built-in object types, such as RegExp, Boolean, etc. By using the methods and properties provided by these built-in object types, we can process various types of data more conveniently and complete the execution of various tasks.

The above is the detailed content of What are the built-in object types in js?. For more information, please follow other related articles on the PHP Chinese website!