js tostring 方法

object.toString()

let arr = [1, 2, 3];
console.log(arr.toString()); // 输出: "1,2,3"

let num = 15;
console.log(num.toString(2)); // 输出: "1111" (二进制)
console.log(num.toString(16)); // 输出: "f" (十六进制)

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

class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }

  toString() {
    return `${this.name} is ${this.age} years old.`;
  }
}

let person = new Person('Alice', 30);
console.log(person.toString()); // 输出: "Alice is 30 years old."

try {
  console.log(null.toString());
} catch (e) {
  console.error(e); // TypeError: Cannot read properties of null (reading 'toString')
}

let value = null;
if (value !== null && value !== undefined) {
  console.log(value.toString());
} else {
  console.log('Value is null or undefined');
}

let obj = { name: 'Alice' };
console.log(obj?.toString() || 'Object is not defined'); // 输出: "[object Object]" 或自定义消息