javascript - 检查数组的更多元素是否具有相同的 key 值，是否删除了一个？

Question

所以我已经尝试了我所知道的一切。使用 map 和过滤器、原型(prototype)。没用。 .

[{"color":"black","type":"bmw"},{"color":"gray","type":"golf"}, {"color":"red","type":"bmw"}, {"color":"black","type":"mercedes"}] 

所以我想要实现的是，当我使用javascript执行ajax时，检查两个或多个对象是否具有相同的类型值，例如，如果有两个或多个宝马，则删除其他对象并推送一个宝马类型的物体。希望我说得足够清楚。提前致谢

Answer 1

function removeDuplicates(arr) {
  var alreadyExist = {};           // hash object to keep track of elemnt that have already been encountered
  var indexes = [];                // array of indexes that will be removed
  arr.forEach(function(o, i) {     // for each object o in arr
    if(alreadyExist[o.type])       // if the type of the object o at index i already exist
      indexes.push(i);             // mark its index i to be removed later
    else                           // if not
      alreadyExist[o.type] = true; // then mark the object as found so other ones will be removed
  });
  
  // for each index in the indexes array
  for(var i = 0; i < indexes.length; i++)
    arr.splice(indexes[i] - i, 1); // remove the object at that index ( - i because the array arr is continually changing. Its length decrease every time we remove an item)
}

var array = [{"color":"black","type":"bmw"},{"color":"gray","type":"golf"}, {"color":"red","type":"bmw"}, {"color":"red","type":"bmw"}, {"color":"red","type":"bmw"}, {"color":"black","type":"mercedes"}];

removeDuplicates(array);

console.log(array);