A very good querySelector / querySelectorAll / getElementById / getElementByName / etc. wrapper.

SqS.js

//Some constants.
const ALL=true,ONLY_ONE=false;

//getElementById quick wrapper.
const gEt=id=>document.getElementById(id);

//The actual stuff.
function SqS(selector,amount=ONLY_ONE,root=document){
	if(selector instanceof Node)
		return selector;
	if(!('string'==typeof selector || selector instanceof String))
		return false;
	
	let results
		,selectorInfo={
			rest:selector.slice(1)
			,isComplex:false
		};
	for(let complexChar of [' ','>',':','[','.','#',',','+','~'])
		if(selectorInfo.rest.includes(complexChar)){
			selectorInfo.isComplex=true;
			break;
		}
	
	if(selectorInfo.isComplex)
		if(!amount||amount===1)
			return root.querySelector(selector)
		else if(amount===true)
			return root.querySelectorAll(selector);
		else results=root.querySelectorAll(selector);
	else switch(selector[0]){
	case '#':
		return document.getElementById(selectorInfo.rest);
	case '.':
		results=root.getElementsByClassName(selectorInfo.rest);
		break;
	case '[':
		let nameMatch=/^\[name="([^"]*)"\]$/.exec(selector);
		if(nameMatch)
			results=document.getElementsByName(nameMatch[1]);
		break;
	case ':':
		break;
	default:
		results=root.getElementsByTagName(selector);
	}
	
	//results is falsey (null) when the selector is a pseudoclass, or is '[name=""]'.
	if(!amount||amount===1)
		return results?results[0]:document.querySelector(selector);
	else if(amount===true)
		return results?results:document.querySelectorAll(selector);
	else{
		if(!results)
			results=document.querySelectorAll(selector);
		if(amount>=results.length)
			return results;
		//Remember results is not an array, but a NodeList, and this is faster than [].splice.call(...
		let chosen=[];
		for(let i=0;i<amount;i++)
			chosen.push(results[i]);
		return chosen;
	}
}