how to convert input field value to base64 encode or decode in angular js

Use the btoa() function to encode:

console.log(btoa("test"));

To decode, you can use the atob() function:

console.log(atob("dGVzdA=="))

https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding

<input type="text" [(ngModel)]="mymodel" class="form-controle" id="myid" />
var string = $('#myid').val();
var encodedString = btoa(string);
console.log(encodedString);
var decodedString = atob(encodedString);
console.log(decodedString);