// 3 persons //different fields //fields check

let a = {
    "name": "Jimmy",
    "surname": "Dick",
    };
    a.sex = "male";
    let b = {
    "name": "Sara",
    "surname":"Conor",
    };
    b.fathername = "Leonidovna"
    let c = {
    "name": "Stan",
    "surname": "Jopa",
    };
    c.age = 18;
    if ("sex" in a  ){
        alert("Sex in a")
    }if ("fathername" in  b  ){
        alert("fathername in b")
    }if ("age" in  c ){
        alert("age in c")}
    
    // array of persons
    
            a = {
            "name": "Jimmy",
            "surname": "Dick",
            
            },
            b = {
            "name": "Sara",
            "surname":"Conor",
            
            },
            c = {
            "name": "Stan",
            "surname": "Jopa",
            
            }
    let persons = [a, b, c];
        let d = {
        "name":"Gregor",
        "surname":"Clit",
        
      };
      persons.push(d)
      
    
    
    // loop of persons
    
    for(let i in persons){
        console.log(persons[i])
    };
    
    // loop of name and surname
    
    for( i in persons){
        console.log(persons[i].name, persons[i].surname);
    }
    
    // loop of loop of values 
    
    for( i in persons){
        for(values in persons[i]){
    console.log(persons[i][values])}}
    
    // fullName???
    
    if("fathername" in a ){
        persons[0].fullName = "fullName"
    }else if("fathername" in a ){
        persons[1].fullName = "fullName"
    }else if("fathername" in a ){
        persons[2].fullName = "fullName"
    }else if("fathername" in a ){
        persons[3].fullName = "fullName"
    }
    
    // serialize
    
    JSON.stringify(persons)
    
    '[{"name":"Jimmy","surname":"Dick"},{"name":"Sara","surname":"Conor"},{"name":"Stan","surname":"Jopa"},{"name":"Gregor","surname":"Clit"},{"name:"Billy","surname":"Herington"}]'
    
    let jsPersons = JSON.stringify(persons)
    
    // deserialize
    
    jsPersons ='[{"name":"Jimmy","surname":"Dick"},{"name":"Sara","surname":"Conor"},{"name":"Stan","surname":"Jopa"},{"name":"Gregor","surname":"Clit"},{"name":"Bill","surname":"Didi"}]'
    let objPersons = JSON.parse(jsPersons)
    
    // HTML/ HTML optional fields/ HTML tr color
    
    // let a = {
    //     "name": "Jimmy",
    //     "surname": "Dick",
    //     };
    //     a.sex = "male";
    //     let b = {
    //     "name": "Sara",
    //     "surname":"Conor",
    //     };
    //     b.fathername = "Leonidovna"
    //     let c = {
    //     "name": "Stan",
    //     "surname": "Jopa",
    //     };
    //     c.age = 18;
    //     let persons = [a, b, c];
    //     let d = {
    //     "name":"Gregor",
    //     "surname":"Clit",
    //     "fathername":"Cumguy"
    //   };
    //   persons.push(d)
    
    let str = "<table border='1'>"
    str += "<tr><th>persons</th><th>name</th><th>surname</th><th>age</th><th>fathername</th><th>sex</th></tr>"
    for(let i = 0; i < persons.length; i++){
        if(i % 2 == 0){
            str += `<tr style='background: blue'>
            <td>${i}</td>
            <td>${persons[i]["name"]}</td>
            <td>${persons[i]["surname"]}</td>
            <td>${persons[i]["age"]}</td>
            <td>${persons[i]["fathername"]}</td>
            <td>${persons[i]["sex"]}</td></tr>`
        }
        else{
            str += `<tr style='background: yellow'>
            <td>${i}</td>
            <td>${persons[i]["name"]}</td>
            <td>${persons[i]["surname"]}</td>
            <td>${persons[i]["age"]}</td>
            <td>${persons[i]["fathername"]}</td>
            <td>${persons[i]["sex"]}</td></tr>`
        }
    
    str += "</table>"
    document.write(str)
    
 // destruct array
    
let arr = [1,2,3,4,5, "a", "b", "c"]
let [odd1,even1,odd2,even2,odd3,...letters] = arr;
    
// destruct string
    
let arr1 = [1, "abc"]
let [number] = arr1
let [s1,s2,s3] = arr1[1]
    
// destruct 2
    
let obj = {name: 'Ivan',
               surname: 'Petrov',
               children: [{name: 'Maria'}, {name: 'Nikolay'}]}
    
let [name1,name2] = obj.children;
    
// destruct 3
    
let arr2 = [1,2,3,4, 5,6,7,10]
let [a,b,...length] = arr2