在JavaScript中比较数组的有效方法

Question

I need to compare the elements from two arrays as follows:

arr1[0] ? arr2[0]
arr1[1] ? arr2[1]
arr1[2] ? arr2[2]
etc.

I wrote some code but it seems to be slow when I try to compare 1000 objects like this on each array :

{
   "id":"event707",
   "name":"Custom707",
   "type":"disabled",
   "default_metric":false,
   "participation":"disabled",
   "serialization":"always_record"
}

This is how my function looks like (just an example for two arrays with hard coded data).

function compare() {
  var step = 0;
  var fruits1 = [{"apple":25},{"bannana":36},{"orange":6}];
  var fruits2 = [{"apple":25},{"bannana":36},{"orange":6}];
  for(var i=0;i<fruits1.length;i++) {
    for(var j=step;j<fruits2.length;j++) {
      console.log("FRUIT1");
      console.log(JSON.stringify(fruits1[i]));
      console.log("FRUIT2");
      console.log(JSON.stringify(fruits2[j]));
      console.log("----------------------");
      if(JSON.stringify(fruits1[i])!== JSON.stringify(fruits2[j])) {
        //do something
      }
      step = step + 1;
      break;
    }
  }
}

Answer 1

Simple function without library:

 var arr1 = [1,2,3]; var arr2 = [1,2,4]; //This function takes one item, the index of the item, and another array to compare the item with. function compare(item, index, array2){ return array2[index] == item; } // the forEach method gives the item as first parameter // the index as second parameter // and the array as third parameter. All are optional. arr1.forEach(function(item, index){ console.log(compare(item, index, arr2)); }); 

Combine this with the answer Abdennour TOUMI gave, and you have an object comparison method :)

For simple objects you could use JSON.stringify(obj1) === JSON.stringify(obj2) .

More info on object comparison can be found in this answer

Answer 2

With an invention of Object.prototype.compare() and Array.prototype.compare() this job becomes a very simple task. Array compare can handle both primitive and reference type items. Objects are compared shallow. Let's see how it works;

 Object.prototype.compare = function(o){ var ok = Object.keys(this); return typeof o === "object" && ok.length === Object.keys(o).length ? ok.every(k => this[k] === o[k]) : false; }; Array.prototype.compare = function(a){ return this.every((e,i) => typeof a[i] === "object" ? a[i].compare(e) : a[i] === e); }; var fruits1 = [{"apple":25},{"bannana":36},{"orange":6}], fruits2 = [{"apple":25},{"bannana":36},{"orange":6}]; console.log(fruits1.compare(fruits2)); 

Answer 3

Use underscore array functions. I would go with intersection

http://underscorejs.org/#intersection

Answer 4

You can use the following static method for Object class : Object.equals

 Object.equals=function(a,b){if(a===b)return!0;if(!(a instanceof Object&&b instanceof Object))return!1;if(a.valueOf()===b.valueOf())return!0;if(a.constructor!==b.constructor)return!1;for(var c in a)if(a.hasOwnProperty(c)){if(!b.hasOwnProperty(c))return!1;if(a[c]!==b[c]){if("object"!=typeof a[c])return!1;if(!Object.equals(a[c],b[c]))return!1}}for(c in b)if(b.hasOwnProperty(c)&&!a.hasOwnProperty(c))return!1;return!0}; console.log( `"[1,2,3] == [1,2,3]" ?`,Object.equals([1,2,3],[1,2,3]) ); console.log( `"[{"apple":25},{"bannana":36},{"orange":6}] == [{"apple":25},{"bannana":36},{"orange":6}]" ?`,Object.equals([{"apple":25},{"bannana":36},{"orange":6}], [{"apple":25},{"bannana":36},{"orange":6}]) );