How to register a JavaScript code in Dynamics CRM Form?

We will consider an example where we will trigger the JavaScript code on saving the Account record. Below is the sample code which we will use to trigger the alert after saving the Account record. 

function Test(executionContext) {

var formContext = executionContext.getFormContext();

//Sending Alert. 

alert("Account Form Is Saved!!");

} 

Once your javascript code ready. Navigate to PowerApps ->Solution->New Solution.