anar1811,
var element = document.querySelectorAll('.main-child > td:first-child');
var elem = document.getElementsByClassName('main-child');
function search() {
for (var i = 0; i < element.length; i++) {
elem[i].style.backgroundColor = '';
if (src.value == element[i].innerHTML) {
elem[i].style.backgroundColor = '#666';
}
}
}