"use strict";
function dscount(string, a, b) {
	string = string.toUpperCase();
	a = a.toUpperCase();
	b = b.toUpperCase();
	var target = a + b;
	var count = 0;
	var pos = 0;
	while (true) {
		if (string.indexOf(target, pos) >= 0) {
			count += 1;
			pos = string.indexOf(target, pos) + 1;
		} else {
			return count;
		}
	}
}





console.log(dscount('____cd____cd_______Cd____', 'c', 'd'));
// alert('____CD____CD_______CD____'.indexOf('CD'));
// 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!";
}