JavaScript toString Method Guide

In a string, the toString method is used to convert other data types into a string type. In JavaScript, the toString method can be applied to the following data types:

1. Convert numbers to strings using the Number type.
   Example:

let num = 10;
let str = num.toString();
console.log(str); // 输出 "10"

1. Boolean type: Convert boolean values to strings.
   Example:

let bool = true;
let str = bool.toString();
console.log(str); // 输出 "true"

1. Type of Object: Converting an object to a string. The toString method here often needs to be customized to return the appropriate string representation of the object.

   Example:

let person = {firstName: "John", lastName: "Doe"};
person.toString = function() {
  return this.firstName + " " + this.lastName;
};
let str = person.toString();
console.log(str); // 输出 "John Doe"

1. Array type: Convert an array into a string. Similarly, the toString method often needs to be customized to provide the appropriate string representation of the array.
   Example:

let fruits = ["apple", "banana", "orange"];
fruits.toString = function() {
  return this.join(", "); // 使用逗号和空格分隔数组元素
};
let str = fruits.toString();
console.log(str); // 输出 "apple, banana, orange"

It is important to note that the toString method does not modify the values of the original data types, but instead returns a new string value. As a result, in the example above, the values of the num, bool, person, and fruits variables have not been changed.