What will happen if instead of a class, a regular object with the same methods is used (without strict mode)?

If instead of a class, a regular object with the same methods is used (without strict mode), the main differences will be in behavior when creating instances and inheritance mechanisms.

A class in JavaScript is syntactic sugar over prototypal inheritance. When using a class, you can create new objects via new, which automatically inherit methods from the class prototype.

If you simply create an object with methods, then:

• You cannot use new to create instances because the object is not a constructor.
• Methods will just be properties of the object, not a prototype for new objects.
• There is no automatic binding of this when calling methods through instances, since there are no instances.

Example:

// Class
class User {
  constructor(name) {
    this.name = name;
  }
  greet() {
    console.log(`Hello, ${this.name}`);
  }
}
const u = new User('Alice');
u.greet(); // Hello, Alice

// Regular object
const userObj = {
  name: 'Bob',
  greet() {
    console.log(`Hello, ${this.name}`);
  }
};
userObj.greet(); // Hello, Bob

// But you cannot do new userObj()
// TypeError: userObj is not a constructor

Thus, a class is convenient for creating multiple similar objects with shared methods and inheritance, while an object is just a set of properties and functions.