How to add and remove items from a json easily?

The function below removes the JSON entry by any key.

It will serve you like a glove! ;-) ( demo )

var meuJSON = [{id: 1, titulo: 'compra', valor: 50.00, data:'2014-10-23' },{id: 1, titulo: 'compra', valor: 60.00, data:'2014-10-24' } ];

function removerPela(chave, valor){
    meuJSON = meuJSON.filter(function(jsonObject) {
        return jsonObject[chave] != valor;
    });
    return meuJSON
}

console.log(removerPela("data","2014-10-23"));

If you want to remove all the elements of the array with a certain ID you can do this:

function removerID(id, arr) {
    return arr.map(function (obj) {
        if (obj.id != id) return obj;
        else return false;
    }).filter(Boolean);
}

jsFiddle: link

In this case I suggest you do not change the initial array. You can always do arr = removerID(1, arr); , but if you want to change the array even without passing it to the function you can do the assignment inside the function:

function removerID(id) {
    arr = arr.map(function (obj) {
        if (obj.id != id) return obj;
        else return false;
    }).filter(Boolean);
}

Another alternative is to make a map with indexes of objects that have a certain ID but this only makes the code more complex and I doubt it will greatly improve the performance of qq would be something like this:

function removerID(id) {
    arr.map(function (obj, i) {
        if (obj.id == id) return i;
        else return 'foo';
    }).reverse().map(function (i) { // uso o reverse para ele usar indexes decrescentes
        if (typeof i == 'number') arr.splice(i, 1);
    })
}
removerID(1);

jsFiddle: link

You can do this using the delete function. Take a look at here . Tip: An id is a unique identifier. Do not use the same id for more than one different element.