object Method

let westeros = {
    cersei: 'Lannister',
    arya: 'Stark',
    jon: 'Snow',
    brienne: 'Tarth',
    daenerys: 'Targaryen',
    theon: 'Greyjoy',
    jorah: 'Mormont',
    margaery: 'Tyrell',
    sandor: 'Clegane',
    samwell: 'Tarly',
    ramsay: 'Bolton'
}

//for(let prop of arr)
// foreach( )  filter( ) map() reduce()

let keys = Object.keys(westeros);
console.log('Keys ', keys);
let vals = Object.values(westeros);
console.log('Vals', vals);
let entries = Object.entries(westeros);
console.log('Entries', entries);
console.log(entries[2][1]);

JavaScript Nested Loops with Arrays and Objects

// nested loops and multi-dimensional objects
// We can use nested loops to access all the elements
// inside multi-dimensional arrays or objects

let twoD = [
    [1, 2, 3, 4, 5, 6, 7],
    [8, 10, 5, 7, 3, 22, 6, 42],
    [123, 54, 12, 11, 9, 15]
];

let bigHero = {
    characters: [{
            name: 'Hiro',
            voice: 'Ryan Potter'
        },
        {
            name: 'Baymax',
            voice: 'Scott Adsit',
            prop: 12
        },
        {
            name: 'Go Go Tamago',
            voice: 'Jamie Chung'
        },
        {
            name: 'Fred',
            voice: 'T.J. Miller'
        }
    ]
};

let chars = bigHero['characters']; //bigHero.characters
for (let i = 0, len = chars.length; i < len; i++) {
    //    console.log(chars[i]);
       console.log(chars[i].name);
       console.log(chars[i]['voice']);
    for (let prop in chars[i]) {
        console.log(prop, chars[i].prop, chars[i][prop]);
    }
}

// nested for loops
let rows = twoD.length;
for(let i=0; i<rows; i++){
   let items = twoD[i].length;
//    console.log(i, items)
   for(let n=0; n<items; n++){
       console.log( twoD[i][n] );
   }
}

Destructuring with Promises and Array Methods

Destructuring allows us to see inside an object or array when it is being passed to a function. This can be combined with calls to Array methods and Promise.then methods to great effect.

/*
Destructuring allows us to see inside an object
or array when it is being passed to a function.
This can be combined with calls to Array methods
and Promise.then methods to great effect.
*/
const log = console.log;
let people = [{
        id: 1,
        name: 'Leonard',
        phd: true,
        partner: 'Penny'
    },
    {
        id: 2,
        name: 'Howard',
        phd: false,
        partner: 'Bernadette'
    },
    {
        id: 3,
        name: 'Sheldon',
        phd: true,
        partner: 'Amy'
    },
    {
        id: 4,
        name: 'Raj',
        phd: true,
        partner: 'Cinnamon'
    },
];
let nums = [12, 34, 56, 78, 90];

let n = nums.map((number) => {
    log(number);
});
let ppl = people.map(({
    name: nm,
    partner: pt
}) => {
    log(nm, '&', pt);
});

fetch('./people.json')
    .then((resp) => {
        if (!resp.ok) throw new Error(resp.statusText);
        return resp.json();
    })
    .then(([first, second, ...rest]) => {
        //...rest MUST be the last argument for desctructuring
        // rest[rest.length-1] would be the last element.
        log(first);
        log(second);
    })
    .catch(log);

String Method

/**
 * String.prototype.startsWith(str [,pos]) //returns Boolean
 * String.prototype.endsWith(str [,pos])   //returns Boolean
 *
 * String.prototype.includes(str [,pos])  //returns Boolean
 * String.prototype.indexOf(str [,pos])  //returns -1 or position index
 * String.prototype.lastIndexOf(str [,pos])  //returns -1 or position index
 * String.prototype.charAt(pos)  //returns the single code point at that position
 * String.prototype.match(regExp); //returns an Array of matches or null. regex.test() and regex.exec()
 */
let log = console.log;

let sentence = 'How are you today?👋🏻';
let len = sentence.length;
let regexp = /[Ho]/g;

// log(sentence.indexOf('👋🏻')); //18
// log(sentence.lastIndexOf('👋🏻')); //18
// log(sentence.includes('x')); //false
// log(sentence.match(regexp));// []  or null
// log(regexp.test(sentence)); // true
// log(sentence.charAt(0) === 'H');
// log(sentence.charAt(18));
// log(sentence.substring(18));

log(sentence.startsWith('H'));
log(sentence.startsWith('h'));
log(sentence.startsWith('👋🏻', 18));
log(sentence.endsWith('👋🏻'));

watermark.image?)

startsWith, endsWith, and Finding Strings