function highlight(strings, ...values) {
  return strings.reduce((result, string, i) => {
    const value = values[i] ? `<mark>${values[i]}</mark>` : '';
    return result + string + value;
  }, '');
}

const name = 'Sarah';
const skill = 'React';
const template = highlight`Hello ${name}, you're great at ${skill}!`;

console.log(template);

const str = 'JavaScript';
const result1 = str.slice(-6, -2);
const result2 = str.substring(-6, -2);
const result3 = str.substr(-6, 4);
const combined = [result1, result2, result3];
const final = combined.map(s => s || 'empty').join(' | ');
console.log(final);

const user = {
  name: 'Sarah',
  age: 28,
  city: 'Boston'
};

const keys = Object.keys(user);
const values = Object.values(user);
const entries = Object.entries(user);

const result = entries.map(([key, value]) => {
  return typeof value === 'string' ? key.toUpperCase() : value * 2;
});

console.log(result);

const numbers = [1, 2, 3, 4, 5];
const result = numbers
  .filter(n => n % 2 === 0)
  .map(n => n * 2)
  .reduce((acc, n) => acc + n, 0);

const original = numbers.slice();
original.reverse();

const flattened = [[1, 2], [3], [4, 5]].flat();
const found = flattened.find(n => n > 3);

console.log(result);
console.log(original.length);
console.log(found);

try {
  const obj = null;
  obj.property = 'value';
} catch (e) {
  console.log(e.name);
}

try {
  undeclaredVariable;
} catch (e) {
  console.log(e.name);
}

try {
  JSON.parse('invalid json');
} catch (e) {
  console.log(e.name);
}