freeCodeCamp中一些有趣的方法

1. 过滤对象(找到数组中(collection)与之(source)匹配对象,过滤掉数组中(collection)不匹配对象)

function where(collection, source) {
  var arr = [];
  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;
  });
  // What's in a name?
  
  return arr;
}

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