I have an object that holds alerts and some information about them:

var alerts = { 1: { app: 'helloworld', message: 'message' }, 2: { app: 'helloagain', message: 'another message' }
}

In addition to this, I have a variable that says how many alerts there are, alertNo. My question is, when I go to add a new alert, is there a way to append the alert onto the alerts object?

1

13 Answers

How about storing the alerts as records in an array instead of properties of a single object ?

var alerts = [ {num : 1, app:'helloworld',message:'message'}, {num : 2, app:'helloagain',message:'another message'}
]

And then to add one, just use push:

alerts.push({num : 3, app:'helloagain_again',message:'yet another message'});

1

jQuery $.extend(obj1, obj2) would merge 2 objects for you, but you should really be using an array.

var alertsObj = { 1: {app:'helloworld','message'}, 2: {app:'helloagain',message:'another message'}
};
var alertArr = [ {app:'helloworld','message'}, {app:'helloagain',message:'another message'}
];
var newAlert = {app:'new',message:'message'};
$.extend(alertsObj, newAlert);
alertArr.push(newAlert);

3

You can do this with Object.assign(). Sometimes you need an array, but when working with functions that expect a single JSON object -- such as an OData call -- I've found this method simpler than creating an array only to unpack it.

var alerts = { 1: {app:'helloworld',message:'message'}, 2: {app:'helloagain',message:'another message'}
}
alerts = Object.assign({3: {app:'helloagain_again',message:'yet another message'}}, alerts)
//Result:
console.log(alerts)
{ 1: {app:'helloworld',message:'message'}, 2: {app:'helloagain',message:'another message'} 3: {app: "helloagain_again",message: "yet another message"}
} 

EDIT: To address the comment regarding getting the next key, you can get an array of the keys with the Object.keys() function -- see Vadi's answer for an example of incrementing the key. Similarly, you can get all the values with Object.values() and key-values pairs with Object.entries().

var alerts = { 1: {app:'helloworld',message:'message'}, 2: {app:'helloagain',message:'another message'}
}
console.log(Object.keys(alerts))
// Output
Array [ "1", "2" ]

4

You can use spread syntax as follows..

var alerts = {
1: { app: 'helloworld', message: 'message' },
2: { app: 'helloagain', message: 'another message' } }
alerts = {...alerts, 3: {app: 'hey there', message: 'another message'} }

Now with ES6 we have a very powerful spread operator (...Object) which can make this job very easy. It can be done as follows:

let alerts = { 1: { app: 'helloworld', message: 'message' }, 2: { app: 'helloagain', message: 'another message' }
}
//now suppose you want to add another key called alertNo. with value 2 in the alerts object.
alerts = { ...alerts, alertNo: 2 }

Thats it. It will add the key you want. Hope this helps!!

Like other answers pointed out, you might find it easier to work with an array.

If not:

var alerts = { 1: {app:'helloworld',message:'message'}, 2: {app:'helloagain',message:'another message'}
}
// Get the current size of the object
size = Object.keys(alerts).length
//add a new alert
alerts[size + 1] = {app:'Your new app', message:'your new message'}
//Result:
console.log(alerts)
{ 1: {app:'helloworld',message:'message'}, 2: {app:'helloagain',message:'another message'} 3: {app: "Another hello",message: "Another message"}
} 

try it:

1

You should really go with the array of alerts suggestions, but otherwise adding to the object you mentioned would look like this:

alerts[3]={"app":"goodbyeworld","message":"cya"};

But since you shouldn't use literal numbers as names quote everything and go with

alerts['3']={"app":"goodbyeworld","message":"cya"};

or you can make it an array of objects.

Accessing it looks like

alerts['1'].app
=> "helloworld"

Do you have the ability to change the outer-most structure to an array? So it would look like this

var alerts = [{"app":"helloworld","message":null},{"app":"helloagain","message":"another message"}];

So when you needed to add one, you can just push it onto the array

alerts.push( {"app":"goodbyeworld","message":"cya"} );

Then you have a built-in zero-based index for how the errors are enumerated.

Way easier with ES6:

let exampleObj = { arg1: { subArg1: 1, subArg2: 2, }, arg2: { subArg1: 1, subArg2: 2, }
};
exampleObj.arg3 = { subArg1: 1, subArg2: 2,
};
console.log(exampleObj);

{
arg1: {subArg1: 1, subArg2: 2}
arg2: {subArg1: 1, subArg2: 2}
arg3: {subArg1: 1, subArg2: 2}
}

As an alternative, in ES6, spread syntax might be used. ${Object.keys(alerts).length + 1} returns next id for alert.

let alerts = { 1: {app:'helloworld',message:'message'}, 2: {app:'helloagain',message:'another message'}
};
alerts = { ...alerts, [`${Object.keys(alerts).length + 1}`]: { app: `helloagain${Object.keys(alerts).length + 1}`,message: 'next message' }
};
console.log(alerts);

I'm sorry but i can't comment your answers already due my reputation!...so, if you wanna modify the structure of your object, you must do like Thane Plummer says, but a little trick if you do not care where to put the item: it will be inserted on first position if you don't specify the number for the insertion.

This is wonderful if you want to pass a Json object for instance to a mongoDB function call and insert a new key inside the conditions you receive. In this case I gonna insert a item myUid with some info from a variable inside my code:

// From backend or anywhere
let myUid = { _id: 'userid128344'};
// ..
// .. let myrequest = { _id: '5d8c94a9f629620ea54ccaea'}; const answer = findWithUid( myrequest).exec();
// ..
// ..
function findWithUid( conditions) { const cond_uid = Object.assign({uid: myUid}, conditions); // the object cond_uid now is: // {uid: 'userid128344', _id: '5d8c94a9f629620ea54ccaea'} // so you can pass the new object Json completly with the new key return myModel.find(cond_uid).exec();
}

[Javascript] After a bit of jiggery pokery, this worked for me:

 let dateEvents = ( { 'Count': 2, 'Items': [ { 'LastPostedDateTime': { "S": "10/16/2019 11:04:59" } }, { 'LastPostedDateTime': { "S": "10/30/2019 21:41:39" } } ], } ); console.log('dateEvents', dateEvents);

The problem I needed to solve was that I might have any number of events and they would all have the same name: LastPostedDateTime all that is different is the date and time.

Try this:

alerts.splice(0,0,{"app":"goodbyeworld","message":"cya"});

Works pretty well, it'll add it to the start of the array.

1

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