brackets.js

// Java has this already, don't bother :)
Array.prototype.peek = function() {
    return this[this.length - 1];
}

// Cool, right?
let toClose = o => o.charCodeAt(0) == 40 ? String.fromCharCode(41) : String.fromCharCode(o.charCodeAt(0) + 2);
let toOpen = o => o.charCodeAt(0) == 41 ? String.fromCharCode(40) : String.fromCharCode(o.charCodeAt(0) - 2);

let matches = ['(', '[', '{'],
    closedMatches = matches.map(toClose);

// this sucks :(
export default function checkBrackets(str) {
    let stack = [];
    for (let spot in str) {
        let char = str[spot],
            isOpen = matches.indexOf(char) > -1,
            isClosed = closedMatches.indexOf(char) > -1;

        let open = isOpen ? char : toOpen(char),
            closed = isClosed ? char : toClose(char);
        if(isOpen)
            stack.push(char)
        if(isClosed) {
            let peek = stack.peek();
            if(peek == open)
                stack.pop();
        }
    }
    return stack.length == 0;
}