How can I push into an array if neither values exist? Here is my array:
[
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" }
]
If I tried to push again into the array with either name: "tom" or text: "tasty", I don't want anything to happen... but if neither of those are there then I want it to .push()
How can I do this?
You could extend the Array prototype with a custom method:
// check if an element exists in array using a comparer function
// comparer : function(currentElement)
Array.prototype.inArray = function(comparer) {
for(var i=0; i < this.length; i++) {
if(comparer(this[i])) return true;
}
return false;
};
// adds an element to the array if it does not already exist using a comparer
// function
Array.prototype.pushIfNotExist = function(element, comparer) {
if (!this.inArray(comparer)) {
this.push(element);
}
};
var array = [{ name: "tom", text: "tasty" }];
var element = { name: "tom", text: "tasty" };
array.pushIfNotExist(element, function(e) {
return e.name === element.name && e.text === element.text;
});
For an array of strings (but not an array of objects), you can check if an item exists by calling .indexOf() and if it doesn't then just push the item into the array:
var newItem = "NEW_ITEM_TO_ARRAY";
var array = ["OLD_ITEM_1", "OLD_ITEM_2"];
array.indexOf(newItem) === -1 ? array.push(newItem) : console.log("This item already exists");
console.log(array)It is quite easy to do using the Array.findIndex function, which takes a function as an argument:
var arrayObj = [{name:"bull", text: "sour"},
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" }
]
var index = arrayObj.findIndex(x => x.name=="bob");
// here you can check specific property for an object whether it exist in your array or not
index === -1 ? arrayObj.push({your_object}) : console.log("object already exists")
http://api.jquery.com/jQuery.unique/
var cleanArray = $.unique(clutteredArray);
you might be interested in makeArray too
The previous example is best in saying that check if it exists before pushing. I see in hindsight it also states you can declare it as part of the prototype (I guess that's aka Class Extension), so no big enhancement below.
Except I'm not sure if indexOf is a faster route then inArray? probably.
Array.prototype.pushUnique = function (item){
if(this.indexOf(item) == -1) {
//if(jQuery.inArray(item, this) == -1) {
this.push(item);
return true;
}
return false;
}
I know this is a very old question, but if you're using ES6 you can use a very small version:
[1,2,3].filter(f => f !== 3).concat([3])
Very easy, at first add a filter which removes the item - if it already exists, and then add it via a concat.
Here is a more realistic example:
const myArray = ['hello', 'world']
const newArrayItem
myArray.filter(f => f !== newArrayItem).concat([newArrayItem])
If you're array contains objects you could adapt the filter function like this:
someArray.filter(f => f.some(s => s.id === myId)).concat([{ id: myId }])
Push dynamically
var a = [
{name:"bull", text: "sour"},
{name: "tom", text: "tasty" },
{name: "Jerry", text: "tasty" }
]
function addItem(item) {
var index = a.findIndex(x => x.name == item.name)
if (index === -1) {
a.push(item);
}else {
console.log("object already exists")
}
}
var item = {name:"bull", text: "sour"};
addItem(item);
In simple method
var item = {name:"bull", text: "sour"};
a.findIndex(x => x.name == item.name) == -1 ? a.push(item) : console.log("object already exists")
If the array contains only primitive types/ simple array
var b = [1, 7, 8, 4, 3];
var newItem = 6;
b.indexOf(newItem) === -1 && b.push(newItem);
Use a js library like underscore.js for these reasons exactly. Use: union: Computes the union of the passed-in arrays: the list of unique items, in order, that are present in one or more of the arrays.
_.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
=> [1, 2, 3, 101, 10]
I would suggest you use a Set,
Sets only allow unique entries, which automatically solves your problem.
Sets can be declared like so:
const baz = new Set(["Foo","Bar"])
Not sure about speed, but stringification + indexOf is a simple approach. Start with turning your array into a string:
let strMyArray = JSON.stringify(myArray);
Then for a series of attribute-value pairs you can use:
if (strMyArray.indexOf('"name":"tom"') === -1 && strMyArray.indexOf('"text":"tasty"') === -1) {
myArray.push({ name: "tom", text: "tasty" });
}
Finding a whole object is simpler:
if (strMyArray.indexOf(JSON.stringify(objAddMe) === -1) {
myArray.push(objAddMe);
}
My choice was to use .includes() extending the Array.prototype as @Darrin Dimitrov suggested:
Array.prototype.pushIfNotIncluded = function (element) {
if (!this.includes(element)) {
this.push(element);
}
}
Just remembering that includes comes from es6 and does not work on IE:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes
In case you need something simple without wanting to extend the Array prototype:
// Example array
var array = [{id: 1}, {id: 2}, {id: 3}];
function pushIfNew(obj) {
for (var i = 0; i < array.length; i++) {
if (array[i].id === obj.id) { // modify whatever property you need
return;
}
}
array.push(obj);
}
In case anyone has less complicated requirements, here is my adaptation of the answer for a simple string array:
Array.prototype.pushIfNotExist = function(val) {
if (typeof(val) == 'undefined' || val == '') { return; }
val = $.trim(val);
if ($.inArray(val, this) == -1) {
this.push(val);
}
};
Update: Replaced indexOf and trim with jQuery alternatives for IE8 compatability
I used map and reduce to do this in the case where you wish to search by the a specific property of an object, useful as doing direct object equality will often fail.
var newItem = {'unique_id': 123};
var searchList = [{'unique_id' : 123}, {'unique_id' : 456}];
hasDuplicate = searchList
.map(function(e){return e.unique_id== newItem.unique_id})
.reduce(function(pre, cur) {return pre || cur});
if (hasDuplicate) {
searchList.push(newItem);
} else {
console.log("Duplicate Item");
}
You can use the findIndex method with a callback function and its "this" parameter.
Note: old browsers don't know findIndex but a polyfill is available.
Sample code (take care that in the original question, a new object is pushed only if neither of its data is in previoulsy pushed objects):
var a=[{name:"tom", text:"tasty"}], b;
var magic=function(e) {
return ((e.name == this.name) || (e.text == this.text));
};
b={name:"tom", text:"tasty"};
if (a.findIndex(magic,b) == -1)
a.push(b); // nothing done
b={name:"tom", text:"ugly"};
if (a.findIndex(magic,b) == -1)
a.push(b); // nothing done
b={name:"bob", text:"tasty"};
if (a.findIndex(magic,b) == -1)
a.push(b); // nothing done
b={name:"bob", text:"ugly"};
if (a.findIndex(magic,b) == -1)
a.push(b); // b is pushed into a
I guess i am too late to answer here however this is what i finally came up with for a mail manager i wrote. Works that's all i need.
window.ListManager = [];
$('#add').click(function(){
//Your Functionality
let data =Math.floor(Math.random() * 5) + 1
if (window.ListManager.includes(data)){
console.log("data exists in list")
}else{
window.ListManager.push(data);
}
$('#result').text(window.ListManager);
});<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<h1>Unique List</h1>
<p id="result"></p>
<button id="add">Add to List</button>If you already have an array containing duplicates, transform the array of objects into an array of strings, and then use the Set() function to eliminate duplicates:
// Declaring an array of objects containing duplicate objects
let arrayOfObjects = [{name: "tom", text: "tasty"}, {name: "tom", text: "tasty"}];
// Transforming array of objects into array of strings
let arrayOfStrings = arrayOfObjects.map(obj => JSON.stringify(obj));
// Creating a new set, Set() returns unique values by definition
let uniqueSet = new Set(arrayOfStrings);
// Transforming set into array and reversing strings to objects
let uniqueArrayOfObjects = [...uniqueSet].map(elem => JSON.parse(elem));
console.log(uniqueArrayOfObjects);
// [{name: "tom", text: "tasty"}]
If you don't have duplicates so far and you want to check for duplicates before pushing a new element:
// Declaring an array of objects without duplicates
let arrayOfObjects = [{name: "tom", text: "tasty"}];
// Transforming array of objects into array of strings
let arrayOfStrings = arrayOfObjects.map(obj => JSON.stringify(obj));
// Declaring new element as an example
let newElem = {name: "tom", text: "tasty"};
// Stringifying new element
let newElemString = JSON.stringify(newElem);
// At this point, check if the string is duplicated and add it to array
!arrayOfStrings.includes(newElemString) && arrayOfObjects.push(newElem);
console.log(arrayOfObjects);
// [{name: "tom", text: "tasty"}]
This is working func for an objects comparison. In some cases you might have lot of fields to compare. Simply loop the array and call this function with a existing items and new item.
var objectsEqual = function (object1, object2) {
if(!object1 || !object2)
return false;
var result = true;
var arrayObj1 = _.keys(object1);
var currentKey = "";
for (var i = 0; i < arrayObj1.length; i++) {
currentKey = arrayObj1[i];
if (object1[currentKey] !== null && object2[currentKey] !== null)
if (!_.has(object2, currentKey) ||
!_.isEqual(object1[currentKey].toUpperCase(), object2[currentKey].toUpperCase()))
return false;
}
return result;
};
someArray = [{a: 'a1 value', b: {c: "c1 value"},
{a: 'a2 value', b: {c: "c2 value"}]
newObject = {a: 'a2 value', b: {c: "c2 value"}}
//New object which needs check for duplicity
let isExists = checkForExists(newObject) {
return someArray.some(function(el) {
return el.a === newObject.a && el.b.c === newObject.b.c;
});
}
// write your logic here
// if isExists is true then already object in an array else you can add
The question was a litle bit old, but that my option :
let finalTab = [{id: 1, name: 'dupont'}, {id: 2, name: 'tintin'}, {id: 3, name:'toto'}]; // Your array of object you want to populate with distinct data
const tabToCompare = [{id: 1, name: 'dupont'}, {id: 4, name: 'tata'}]; // A array with 1 new data and 1 is contain into finalTab
finalTab.push(
...tabToCompare.filter(
tabToC => !finalTab.find(
finalT => finalT.id === tabToC.id)
)
); // Just filter the first array, and check if data into tabToCompare is not into finalTab, finally push the result of the filters
console.log(finalTab); // Output : [{id: 1, name: 'dupont'}, {id: 2, name: 'tintin'}, {id: 3, name: 'toto'}, {id: 4, name: 'tata'}];
You can use jQuery grep and push if no results: http://api.jquery.com/jQuery.grep/
It's basically the same solution as in the "extending the prototype" solution, but without extending (or polluting) the prototype.
You can check the array using foreach and then pop the item if it exists otherwise add new item...
sample newItemValue &submitFields are key,value pairs
> //submitFields existing array
> angular.forEach(submitFields, function(item) {
> index++; //newItemValue new key,value to check
> if (newItemValue == item.value) {
> submitFields.splice(index-1,1);
>
> } });
submitFields.push({"field":field,"value":value});
