Tutu_dscount.js

"use strict";
console.clear();

// Yor code here ...
function dscount(str, s1, s2) {
  const pattern = `${s1}${s2}`;
  const regexp = new RegExp(pattern, 'gi');
  let matches;
  let counter = 0;
  while((matches = regexp.exec(str)) != null) {
    regexp.lastIndex = regexp.lastIndex - pattern.length + 1;
    counter++;
  }
  return counter;
}

// Для удобства можно использовать эти тесты:
try {
    test(dscount, ['ab___ab__', 'a', 'b'], 2);
    test(dscount, ['___cd____', 'c', 'd'], 1);
    test(dscount, ['de_______', 'd', 'e'], 1);
    test(dscount, ['12_12__12', '1', '2'], 3);
    test(dscount, ['_ba______', 'a', 'b'], 0);
    test(dscount, ['_a__b____', 'a', 'b'], 0);
    test(dscount, ['-ab-аb-ab', 'a', 'b'], 2);
    test(dscount, ['aAa', 'a', 'a'], 2);

    console.info("Congratulations! All tests success passed.");
} catch(e) {
    console.error(e);
}

// Простая функция тестирования
function test(call, args, count, n) {
    let r = (call.apply(n, args) === count);
    console.assert(r, `Finded items count: ${count}`);
    if (!r) throw "Test failed!";
}

Tutu_practical1

function parseUrl(url) {
  var linkEl = document.createElement('a');
  linkEl.href = url;
  return linkEl;
}

let a = parseUrl('http://tutu.ru:8080/do/any.php?a=1&b[]=a&b[]=b#foo')

// Вернет объект, в котором будут следующие свойства:
console.log( a.href == "http://tutu.ru:8080/do/any.php?a=1&b[]=a&b[]=b#foo" )
console.log( a.hash == "#foo" )
console.log( a.port == "8080" )
console.log( a.host == "tutu.ru:8080" )
console.log( a.protocol == "http:" )
console.log( a.hostname == "tutu.ru" )
console.log( a.pathname == "/do/any.php" )
console.log( a.origin == "http://tutu.ru:8080" )

Tutu_refactor.js

'use strict';
console.clear();

function func(s, a, b) {

	if (s.match(/^$/)) {
		return -1;
	}
	
	var i = s.length -1;
	var aIndex =     -1;
	var bIndex =     -1;
	
	while ((aIndex == -1) && (bIndex == -1) && (i > 0)) {
	    if (s.substring(i, i +1) == a) {
	    	aIndex = i;
    	}
	    if (s.substring(i, i +1) == b) {
	    	bIndex = i;
    	}
	    i = i - 1;
	}
	
	if (aIndex != -1) {
	    if (bIndex == -1) {
	        return aIndex;
	    }
	    else {
	        return Math.max(aIndex, bIndex);
	    }
	}
	
	if (bIndex != -1) {
	    return bIndex;
	}
	else {
	    return -1;
	}
}

function funcRefactored(s, a, b) {
  const aIndex = a.length === 1 ? s.lastIndexOf(a) : -1;
  const bIndex = b.length === 1 ? s.lastIndexOf(b) : -1;
  const maxIndex = Math.max(aIndex, bIndex);
  return maxIndex > 0 ? maxIndex: -1;
}

var args = [
  ['hello', 'e', 'e'],
  ['hello', 'H', 'll'],
  ['hello', 'z', 'x'],
  ['hello', 'o', 'l'],
];

args.forEach(item => {
  console.log(func.apply(null, item), funcRefactored.apply(null, item));
})