React Meetup Talk: I don't know that

array_from.js

function main() {
    return Array.from(
        'Hello World',   // Array like object OR iterable (arguments, Map, Set, String)
        ch => ch + 'c'
    );
}

console.log(main());    //

dotAll_regex.js

function main() {
    return /a\nc/s.test('a#c');
}

console.log(main());    //

// It's very new (ES2018), check for compatibility

finally.js

function main() {
    try {
        throw Error('Error in try');
        return 'Try Me!!';
    } catch (e) {
        return 'Catch Me!!';
    } finally {
        console.log('here');
        //return 'finally';
    }
}

console.log(main());    // 


// Finally is always right (just like a girl :D)

json_stringify_1.js

function main() {
    return JSON.stringify(
        {
            foo: 'bar',
            // hello: {
            //     a: 2,
            // },
            //bar: undefined,
            //bar: [10, undefined]
            //bar: function () { console.log() },
            //bar: [10, function() { console.log()}],
            //bar: Symbol('bar'),
            bar: [10, Symbol('bar')],
        },
        null,
        2
    );
}

console.log(main());

json_stringify_2.js

function main() {
    return JSON.stringify(
        {
            foo: 'bar',
            bar: [10, undefined],
            toJSON () {                 // you can use this to hide sensitive information
                return 'blah blah';
            }
        },
        null,
        2
    );
}

console.log(main());     //

object_keys_predictable_order.js

const obj = {
    '1': 'integer: 2',
    'foo': 'string: foo',
    '01': 'string: 01',
    011: 'string: 01',
    1: 'integer: 1',
    [Symbol('first')]: 'symbol: first'
};
  
obj['0'] = '0';
obj[Symbol('last')] = 'symbol: last';
obj['veryLast'] = 'string: very last';
  
console.log(Reflect.ownKeys(obj));

console.log(Object.keys(obj));

optional_catch_binding.js

function main() {
    try {
        throw Error('Oh my God');    
    } catch {
        return 'Some Error';
    }
}

console.log(main());    //

promise_then.js

Promise.resolve('Hello').then(
    value => { 
        console.log(`Resolution with: ${value}`)    //
    }
);

Promise.resolve(
    { then: 42 }
).then(
    value => { 
        console.log(`Resolution with: ${JSON.stringify(value)}`);   // 
    }
);

Promise.resolve({
    then: (...args) => {
        console.log(args);  // 
        //args[0]('some value')
    }
}).then(
    // This will not be logged
    value => {
        console.log(`Resolution with: ${value}`)    //
    }
);

String_comparison_1.js

function compare() {
    return [
        'aBcD' === 'abcd',
        'åbcd' === 'abcd',
    ]
}

console.log(compare()); //

string_comparison_2.js

function compare() {
    return [
        'aBcD'.localeCompare('abcd', undefined, { sensitivity: 'base'}),
        'åbcd'.localeCompare('abcd', undefined, { sensitivity: 'base'}),
    ]
}

console.log(compare()); //


// Note: This is a very slow function, so use carefully.