How to check if an object is logically in an array, JavaScript

Question

I need to check if an object is logically in an array, when two objects are logically equal (same as equals in Java), it will be considered as "in" the array

While I am using $.inArray of jQuery to check the code below, it retuns -1, indicating that the copied is not being processed as "in" the array.

 var a =[{value: "G27", title: "G27"}]; $.inArray({value: "G27", title: "G27"},a); //returns -1 

The above is just an example. Is there an easy way for general cases to achieve this

Answer 1

A workaround would be to check each key-value pair in a for loop:

 function exist(arr, obj){ var len = Object.keys(obj).length; var count = 0; for(var i=0;i<arr.length;i++){ count=0; for(var key in obj){ if(obj[key] == arr[i][key]){ count++; } } if(count == len && count == Object.keys(arr[i]).length){ console.log("Exists!!"); return; } } console.log("Don't exist!!"); } var arr =[{value: "G27", title: "G27"}]; var b = {value: "G27", title: "G27"}; //Call exist(arr, b); 

Answer 2

If you like to use underscore.js, you can try using _.findWhere() :

 var a = [{value: "G27", title: "G27"}]; snippet.log(_.findWhere(a, {value: "G27", title: "G27"}) !== undefined); // returns true 

 <script src="http://tjcrowder.imtqy.com/simple-snippets-console/snippet.js"></script> <script src="http://underscorejs.org/underscore-min.js"></script> 

Answer 3

You can use the array filtering method.

 var arr = [{value: "G27", title: "G27"}]; // Don't call filter on arr because this will mutate arr itself. Instead of creating a new array. var filteredArr = Array.prototype.filter.call(arr, function(item) { return item.value == "G27" && iem.title == "G27"; }); if(filteredArr.length > 0) { // Item exists } 

Answer 4

You can try an individual search:

 var indexOf = function(array, obj) { var i = array.length; var o; while (o = array[--i]) //note, its assignment if (obj.value === o.value && obj.title === o.title) break; return i; }; var arr = [{ value: "G27", title: "G27" }, { value: "G28", title: "G28" }, { value: "G29", title: "G29" }]; console.log(indexOf(arr, { title: "G28", value: "G28" })); //<-- 1 console.log(indexOf(arr, { title: "G30", value: "G30" })); //<-- -1