User:SlyAceZeta/common.js

var mutNode = document.getElementsByClassName('wds-global-navigation__search-input')[0];
var mutConfig = { attributeFilter: ['placeholder'] };

var mutObserver = new MutationObserver(mutCallback);
function mutCallback(mutations) {
	for (let mutation of mutations) {
		if (mutation.type === 'attributes') {
			mutNode.setAttribute('placeholder', "Search Assassin's Creed Wiki...");
		}
	}
}

mutObserver.observe(mutNode, mutConfig);