CODEWITHSUNDEEP
javascriptcallback
Roland
Roland

Reputation: 9701

Callback function that accepts more parameters

I have the following method added to an object :

loadAPIServiceData : function(service, format, term, callback) {
        return $.when($.ajax({
            url: service + ((term) ? term : '') + '?format=' + format
        })).done(function(result) {
            return callback.apply(result, [ result ]);
        });
    },

The callback function is passed one parameter that I need further down in the chain when I'm loading the data ( the result obviously gets whatever I get back from the AJAX call ). What I need is to be able to add more parameters to the callback function when it's called, and still have the result in there :)

To be more explicit about it this is what I was meaning when I said "I need is to be able to add more parameters to the callback function when it's called, and still have the result in there" :

var test = loadAPIServiceData('some_service', 'json', 'some_term', function(result, another_parameter, ...) {

});

Upvotes: 0

Views: 132

Answers (2)

BAK
BAK

Reputation: 1005

You can use bind for apply arguments without need to modify the loadAPIServiceData:

function myCallback(arg1, arg2, result) {
    //
}

loadAPIServiceData(service, format, term, myCallback.bind(this, arg1, arg2));

If you prefer keep result in first arg position, this code send all additional argument to the callback, using the arguments object:

loadAPIServiceData : function(service, format, term, callback) {
    var add_args = Array.prototype.slice.call(arguments, 4);

    return $.when($.ajax({
        url: service + ((term) ? term : '') + '?format=' + format
    })).done(function(result) {
        return callback.apply(this, result, [ result].concat(add_args));
    });
},

function myCallback(result, arg1, arg2) {
    //
}

loadAPIServiceData(service, format, term, myCallback, "arg1", "arg2");

Upvotes: 1

lostsource
lostsource

Reputation: 21830

Not sure if I understood your question correctly but does this make sense?

function addOptionalParams(result) {
    var params = [];
    params.push(result);

    // do logic to decide if you need more params
    // if you need more params, push them to the params array
    if(weNeedMoreParams) {
        params.push('foo');
        params.push('bar');
    }

    return params;
}

loadAPIServiceData : function(service, format, term, callback) {
    return $.when($.ajax({
        url: service + ((term) ? term : '') + '?format=' + format
    })).done(function(result) {
        var callbackArgs = addOptionalParams(result);

        return callback.apply(this, callbackArgs);
    });
},

It is the 'done' function which determines which parameters it will invoke the callback with.

Upvotes: 0

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