比较具有相同对象的 2 个 JSON 文件

Question

So I have 2 jSON files, both with same set up and same objects, difference is one has old data that is not updated, the other one has real-time data that is updated in real time, I'd like to subtract the old data with the new data, and output the result.

Code I used that ISN'T successful:

jQuery.getJSON(liveDataURL, function(liveData){

    jQuery.getJSON(oldDataURL, function(oldData){

        liveData.sort(function(a, b){
             return a.number - b.number;
        }).reverse();
        oldData.sort(function(a, b){
             return a.number - b.number; 
        }).reverse();

        var newList = liveData.number - oldData.number;
        console.log(newList);
    });

Any help is appreciated!

Answer 1

What do you mean by subtract?

a = {foo: 17, bar: 12, baz: false} b = {foo: 17, bar: 10}

what does "a - b" mean?

Assuming:

"a - b" := {bar: 12, baz: false}

Something like this will work:

const delta = (a, b) => {
  const d = {};
  Object.keys(a).forEach(key => {
    if (typeof a[key] === 'object') {
      d[key] = delta(a[key], b[key] || {});
      if (d[key] === undefined) {
        delete d[key];
      }
    } else {
      if (a[key] !== b[key]) {
        d[key] = a[key];
      }
    }
  });
  return Object.keys(d).length ? d : undefined;
};

Answer 2

var newList = liveData.number - oldData.number;

This is the wrong way to find difference between list. Just do this, if you want to find the difference of numbers

Assuming the length of both list is same.

var newList = [];
for (var i = 0; i < liveData.length; i++){
    newList.append(liveData[i].number - oldData[i].number);
}