week4.js

// Normal function
function isNotEmpty(paper) {
    return paper !== "";
}

// Arrow function
const isNotEmpty = (paper) => {
    return paper !== "";
}

// Arrow function no parenthesis
const isNotEmpty = paper => {
    return paper !== "";
}

// Arrow function no curly brackets or return
const isNotEmpty = paper => paper !== "";

// Arrow function shortened parameter name
const isNotEmpty = p => p !== "";

// We could use it with filter
const fullPapers = papers.filter( p => p !== "" )

// internFunction( bobCallbackFunction )


const emailList = [
    {
        id: 234,
        author: {
            firstName: "Natalie",
            lastName: "Childs"
        },
        to: "Calvin",
        message: "Heyyyy",
        read: false,
        tags: [
            "not important",
            "personal"
        ]
    },
    {
        id: 1654,
        author: {
            firstName: "Natalie",
            lastName: "Childs"
        },
        to: "Calvin",
        message: "What's up?",
        read: true,
        tags: [
            "work"
        ]
    },
    {
        id: 474,
        author: {
            firstName: "Dylan",
            lastName: "Green"
        },
        to: "Calvin",
        message: "Good day",
        read: false,
        tags: []
    }
]

// Display the Emails - Map
const displayEmails = emailList.map( email => email.author.firstName + ": " + email.message );
alert("Here are the emails:\n" + displayEmails.join("\n") );


// Mark All As Read - ForEach

// We could do it with a for loop
// for(let i = 0; i < emailList.length; i++) {
//     emailList[i].read = true;
// }

// We could do it with for-of
// for( const email of emailList ) {
//     email.read = true;
// }

// Experienced developers would probably use forEach in this situation
emailList.forEach( email => email.read = true );


// Find an Email - Find
const emailFromNatalie = emailList.find( email => email.author.firstName === "Natalie" )


// Really Common
const idOfEmailToDelete = 1654;
const emailToDelete = emailList.find( email => email.id === idOfEmailToDelete )
// deletes it


// Find All Emails From One Person - Filter
const allEmailsFromNatalie = emailList.filter( email => email.author.firstName === "Natalie" )


// All Unread
const allUnreadEmails = emailList.filter( email => !email.read )