Mailbox

class MailBox {
    constructor() {
        this.mailbox = [];
    }
    addMessage(subject,text) {
        this.mailbox.push(subject,text);
        return this;

    }
    get messageCount() {
        return this.mailbox.length/2;
    }
    deleteAllMessages() {
        return this.mailbox = [];
    }
    findBySubject(substr) {
        let arr = [];
        for (let i = 0; i < this.mailbox.length; i+=2) {
            if (this.mailbox[i].indexOf(substr) !== -1) {
                arr.push({subject:this.mailbox[i],text:this.mailbox[i+1]});
            }
        }
        if(arr.length==0) {
            return [];
        }
        return arr
    }
    toString() {
        if(this.mailbox.length==0) {
            return ` * (empty mailbox)`
        }
        let result ='';
        for (let i = 0; i < this.mailbox.length; i+=2) {
            result+=` * [${this.mailbox[i]}] ${this.mailbox[i+1]}\n`

        }

        return result

    }
}

let mb = new MailBox();
console.log("Msg count: " + mb.messageCount);
console.log('Messages:\n' + mb);
mb.addMessage("meeting", "Let's meet at 17/11");
mb.addMessage("beer", "Wanna drink beer tomorrow?");
mb.addMessage("question", "How to solve this problem?");
mb.addMessage("Sofia next week", "I am in Sofia next week.");
console.log("Msg count: " + mb.messageCount);
console.log('Messages:\n' + mb);
console.log("Messages holding 'rakiya': " +
    JSON.stringify(mb.findBySubject('rakiya')));
console.log("Messages holding 'ee': " +
    JSON.stringify(mb.findBySubject('ee')));

mb.deleteAllMessages();
console.log("Msg count: " + mb.messageCount);
console.log('Messages:\n' + mb);

console.log("New mailbox:\n" +
    new MailBox()
        .addMessage("Subj 1", "Msg 1")
        .addMessage("Subj 2", "Msg 2")
        .addMessage("Subj 3", "Msg 3")
        .toString());