// 빌더패턴 const User = class { constructor(build) { if(build) { this.id = build.id; this.name = build.name; this.age = build.age; } } static get Builder() { class Builder { setId(id) { this.id = id; return this; } setName(name) { this.name = name; return this; } setAge(age) { this.age = age; return this; } build() { return new User(this); } } return new Builder(); } } const builder = User.Builder;..