A (probably inefficient) functional approach to determine if any object contains a specific value for a property in an array of objects. Very Haskelly.

existsInAny.js

var existsInAny = function(needle, propertyName, haystack){
    return haystack.map(function(el){return el[propertyName] === needle;}).reduce(function(a,b){return a||b;});
}

/*
# CoffeeScript version
existsInAny = (needle, propertyName, haystack) -> 
    haystack.map((el)-> el[propertyName] is needle).reduce((a,b)-> a||b)
*/