How to access variable from one component into another component in angular?

Question

我现在有两个组件users_profile_component和userslist组件，我想访问使用@viewchild @Input尝试过的userslist组件中的user_profile_component中的is_added变量，但每次它给我带来无法定义错误的错误时，

Answer 1

Angular Services is exactly what you need. Tons of tutorials on the web, here's one: https://angular.io/tutorial/toh-pt4

Answer 2

The first question in this problem is know where is that variable, in the parent? in the child?.

If you want to hace access from the child component to a parent's property, you must use bindings

class Parent {
   property = 1;
}

//
// Parent HMTL
<child [prop]="property">

class Child {
@Input() prop;
  ngOnInit() {
    console.log (this.prop); // 1
  }
}