获取两个javascript对象的增量

Question

我有两个大的,嵌套的javascript对象,我想比较它们并创建一个只代表差异的对象.我打算用它来创建一个PATCH请求.

给定oldObj和newObj:

• 仅打开的属性newObj应该在diff中
• 仅打开的属性oldObj应该在diff中
• newObj如果值是数组,字符串或数字,则两个对象上的属性应使用值
• 应该递归地比较对象
• 无需动态合并阵列,完全替换即可

这可能看起来像重复,但我认为不是.此解决方案(1)仅为一级深度(下面的答案是非递归的,在阵列上爆炸,并且不是双向的).这个解决方案(2)返回不变的属性不是双向的.

目标输入/输出:

diff({a:1},{a:0}); // {a:0}

diff({a:1},{b:1}); // {a:1,b:1}

diff({
  a: { x: 1 },
  b: 1
},
{
  a: { x: 0 },
  b: 1
}) // {a:{x:0}}

diff({a:[1,3,5,7]},{a:[1,3,7]}); // {a:[1,3,7]} 

我正在使用从解决方案1修改的以下方法.它符合所有条件,diff({a:1},{b:1}) // {a:1,b:1}因为它只在一个方向上进行比较.

jsonDiff = function(oldObject, newObject) {
  var diff, i, innerDiff;
  diff = {};
  for (i in newObject) {
    innerDiff = {};
    if (_.isArray(newObject[i])) {
      if (!_.isEqual(newObject[i], oldObject[i])) {
        diff[i] = newObject[i];
      }
    } else if (typeof newObject[i] === 'object') {
      innerDiff = jsonDiff(oldObject[i], newObject[i]);
      if (!_.isEmpty(innerDiff)) {
        diff[i] = innerDiff;
      }
    } else if (!oldObject) {
      diff[i] = newObject[i];
    } else if (!oldObject.hasOwnProperty(i)) {
      diff[i] = newObject[i];
    } else if (oldObject[i] !== newObject[i]) {
      diff[i] = newObject[i];
    }
  }
  return diff;
};

我见过jsonDiffPatch库,但我不需要它创建的所有元数据,只需要原始的diff对象.这是一个迷你图书馆吗？看起来很有必要实现PATCH,但我找不到一个.任何人都有一个小小的要点吗？

Answer 1

这个答案有点长，但我还没有发布。

function monitor(obj, callBack){


var api={
        patch: patchObjectWithDiff, 
        init: init, 
        resolve: resolve, 
        snapshot: snapshot, 
        diff: diff, 
        update: changeMonitor 
   };



function merge2(o, ob) {
     for (var z in ob) {
        if (ob.hasOwnProperty(z)) {
           if(typeof ob[z]=="object"){ 
                if(ob[z]==null){
                    delete o[z];
                }else{
                    merge2( o[z] || {},  ob[z]);
                }

            }else{
                 o[z] = ob[z];
            }

        }
    }
    return o;
}






function snapshot(obj) { 
    var out = [];
    function merge3(ob, path) {
        path = path || [];
                var tp;
        for(var z in ob) {
            if(ob.hasOwnProperty(z)) {
                if(ob[z] && typeof ob[z] == "object" && [Date, RegExp].indexOf(ob[z].constructor) == -1) {

                                        tp=path.concat(z);
                    out.push({
                                                path:  tp.join("`"),
                                                path2:  tp,
                                                dt:  "set",
                                                date:  +new Date,
                                                v: Array.isArray(ob[z]) ? "[]" : "{}"
                                        });

                    merge3(ob[z], path.concat(z));
                } else {
                                        tp=path.concat(z);
                    out.push({
                                                path:  tp.join("`"),
                                                path2:  tp,
                                                type:  "set",
                                                dt:  +new Date,
                                                v: JSON.stringify(ob[z]) 
                                        });
                }
            }
        }
    }

    merge3(obj);
    return out;
};



function diff(d1, d2){

  var out=d2.filter(function(a,b,c){
     var ov=JSON.stringify(a.v);
     return d1.some(function(aa,bb){ return aa.path==a.path && JSON.stringify(aa.v) != ov;  });
  }),

  // find deletions
  dels=d1.filter(function(a,b,c){
     return !d2.some(function(aa,bb){ if(aa.path==a.path ){  return true; };  });
  }),

  allPaths=dels.map(function(a){return a.path}).sort(),

  dels2=dels.filter(function eliminateUnneededSubBranches(a){

        var pos=allPaths.indexOf( a.path2.slice(0,-1).join("`") );

        return pos==-1 || pos >= allPaths.indexOf(a.path);

  }).map(function(a){a.type="del"; delete a.v; return a;});


  [].push.apply(out, dels2);


 //find inserts


var outNew=d2.filter(function(a,b,c){
     var ov=JSON.stringify(a.v);
     return !d1.some(function(aa,bb){ return aa.path==a.path  });
  });

 [].push.apply(out, outNew);



  return out.map(function(a){
       var x= {
         dt: a.dt,
         k: a.path2
       };

       if(a.hasOwnProperty("v")){ x.v=a.v; }

       return x;

            a.k=a.path2; 
            delete a.path; 
            delete a.path2; 
            delete a.type;
      return a;
  });
}



function resolve(path, object){
  var tob=object;
  path.map(function(a){ return (tob=tob[a])||tob; })
 return tob;
}








function patchObjectWithDiff(diff, object){

  diff.forEach(function(a,b,c){
       var p= resolve(a.k.slice(0,-1), object), 
           k= a.k.slice(-1)[0];

       if(a.hasOwnProperty("v")){ //set:
              p[k]=JSON.parse(a.v);
             if(String(p[k]).match(/Z$/)){ p[k]=new Date(''+p[k]) || p[k]; }
        }else{ // del:
           if(Array.isArray(p)){ p.splice(k,1); }else{ delete p[k]; }
       }
  });

   return object;
}











    var init=snapshot(JSON.parse(JSON.stringify(obj))),
          id=Math.random()+ Number(new Date());


    var init=snapshot(obj);

    function changeMonitor(){
        var thisTime=snapshot(obj),
               diffs=diff(init, thisTime);
        if(diffs.length){  
            api.diffs=diffs;
            (callBack||console.log.bind(console))("objectUpdate", diffs );
            init=thisTime;
        }//end if change?
    }

    setInterval(changeMonitor, 2500);

 return api;

}

演示/示例用法：

var obj={a:1, b:[1,2,3], c: false}; // a model object
var dupe=JSON.parse(JSON.stringify(obj)); // a cheap clone of the data for demo use

//subscribe this object to updates    
var mon=monitor(obj, function(type, changes){console.log(type,  changes); });

// make some changes to the object:
obj.e="cool!";
obj.b.push(5);
obj.a=7;

// manually call update instead of waiting for the bundler:
mon.update();

// now apply stored changes to the clone of the orig data:
var updatedDupe= mon.patch(mon.diffs, dupe);

// use a cheap and easy but not production-reliable to compare the objects:
JSON.stringify(updatedDupe)==JSON.stringify(obj); // should be true

在 Chrome 和 Firefox 中进行了测试。

请注意，这个特定的演示对 JSON 的使用取决于一些运气和一致的键排序，而 JS 规范并不能保证这一点。键顺序并不重要，但它可能会导致 JSON.stringify() == 比较失败，即使对象的属性确实是同步的。这只是为了演示，如果有效的话可以得到正确/错误的答案，不要打败我......

更改列表中的所有差异都带有三个键：

  {"dt":1392348959730,"k":["b","3"],"v":"5"}
dt: a timestamp of when the change was discovered
k: the key path where the change was detected
v: what the discovered changed value is as of dt

这个脚本很热门，我没有时间编写适当的文档，但我认为它可能会有所帮助，或者至少会激发一个适合您的解决方案。