COMMUNICATING WITH CHILD COMPONENT

First, we will see how to transfer data from a parent component to a child component. This is probably the most common method of data sharing from parent to child component. It works by using @input life cycle hook and property binding. So let’s get started.

STEP 1:

Initially, declare a variable in child component with the decorator @input. As shown below:

Note: Input class must be imported from angular core

child.component.ts

Data type of input can be anything i.e. a string, a number, or an object. I used any to make it more generic.

STEP 2:

In Child.component.html show dynamic Contact Name through interpolation:

child.component.html

STEP 3:

In parent component, declare an object with contact information:

Below are the results in the browser:

RESULT:

By following the above process, you can transfer data from a parent component to any child component in Angular.

 

COMMUNICATION WITH PARENT COMPONENT

We have now seen how to send data into a child-component. In this process, we will cover how to pass data back to parent component from child component below.

STEP 1:

Initially, declare an event with @output decorator in child component as shown below:

Note: EventEmitter and Input class must be imported from Angular Core library.

child.component.ts

STEP 2:

Add a button in the child component html to trigger this event:

child.component.html

STEP 3:

Now, we will have parent component listen to that child event. For this, add another event handler to the child component element:

Parent.component.html

STEP 4:

Define the function in parent component which will listen to the event. I have declared a string variable in the parent component which text will change on click event in child and data will update with what will be pass from child component:

Parent.component.ts

RESULT:

Before click:

After click:

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