Where art thou

function where(collection, source) {
  var arr = [];
  // What's in a name?
  var keys = Object.keys(source);
  arr = collection.filter(function(item){
    for (var i = 0; i < keys.length; i ++){
      if(!item.hasOwnProperty(keys[i]) || item[keys[i]] !== source[keys[i]]){
        return false;
      }
    }
          return true;
  });

  return arr;
}

where([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" });

另外一种方法

function where(collection, source) {
  var arr = [];
  // What's in a name?
  var keys = Object.keys(source);
  arr = collection.filter(function(item){
    return keys.every(function(key){
      return item.hasOwnProperty(key) && item[key] === source[key];
    });
  });
  return arr;
}

where([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" });