匹配 Json 键并替换为数组中的值

Question

So given a simple json object

[
  {"a": 1},
  {"b": 2},
  {"c": 3},
  {"d": 4}
]

and an array like this

var arr = ["A", "B", "C"];

I want to write the most efficient function to match the lower case keys with their upper case counter parts and replace them with the uppercase letters, I started by turning the array into a object so I wont have to iterate over and over again, but Im stuck. Can someone please show me how they would handle this in the most efficient way?

Answer 1

Without further information on your amount of keys/possible keys, trying to make a generic solution would be like this:

 var arr = [ {"a": 1}, {"b": 2}, {"c": 3}, {"d": 4} ] var match = ["A", "B", "C"]; var objMatch = {} for(var i=0;i<match.length;i++) objMatch[match[i].toLowerCase()] = match[i] // pass it to an object for efficient matching for(var i=0;i<arr.length;i++){ for(var key in arr[i]){ // check if we need to replace the key if(objMatch.hasOwnProperty(key)){ var temp = arr[i][key] // keep old value delete arr[i][key] // delete key arr[i][objMatch[key]] = temp // set new key with same old value } } } console.log(arr)

Answer 2

var a=[
 {"a": 1},
 {"b": 2},
 {"c": 3},
 {"d": 4}
];

var arr = ["A", "B", "C"];

Define a method in Object's prototype chain to rename Object keys:

Object.prototype.changeKey = function (oName, nName) {
   if (oName == nName) {
       return this;
   }
   if (this.hasOwnProperty(oName)) {
      this[nName] = this[oName];
      delete this[oName];
   }
 return this; 
};

Then find the key which matches the elements of array, then change it:

for(var i=0;i<arr.length;i++){
   for(key in a[i]){
   if(key === arr[i].toLowerCase()){a[i].changeKey (key,arr[i])}
  }
}

Here is a fiddle

Answer 3

You could use an helper object and loop throu all items and all keys.

 var arr0 = [{ "a": 1 }, { "b": 2 }, { "c": 3 }, { "d": 4 }], arr1 = ["A", "B", "C"], obj = Object.create(null); arr1.forEach(function (a) { obj[a.toUpperCase()] = a; }); arr0.forEach(function (a) { Object.keys(a).forEach(function (k) { var v = a[k]; if (k.toUpperCase() in obj) { delete a[k]; a[obj[k.toUpperCase()]] = v; } }); }); document.write('<pre>' + JSON.stringify(arr0, 0, 4) + '</pre>');

Answer 4

From what i understand from your question

var arrayOne = [
{"a": 1},
{"b": 2},
{"c": 3},
{"d": 4}
];
var arrayTwo = ["A", "B", "C"];
var tempArray = {};
$.each(arrayOne, function(key,value){
  for(arrayOneKey in value){
    $.each(arrayTwo, function(index,vl) {
      if(vl.toLowerCase() == arrayOneKey.toLowerCase()){
        tempArray[vl]=key+1;
      }
    });
  }
});
console.log(tempArray);

Answer 5

Don't make things complicated. Use map and return a new array:

function transform(arr, keys) {
  return arr.map(function(el) {
    var obj = {};
    var key = Object.keys(el)[0];
    var uc = key.toUpperCase();
    obj[keys.indexOf(uc) > -1 ? uc : key] = el[key];
    return obj;
  });
}

transform(input, arr);

DEMO