Sending arguments to the json_callback function

Question

Sending arguments to the json_callback function

I am utilizing a reverse geolocation technique using MapQuest that is structured as follows:

function fieldVia_changed(a)
            {
                if (document.getElementsByName("via"+a)[0].value.trim().length!=0)
                {
                   var via = document.getElementsByName("via"+a)[0].value ;
                   var strV = via.replace(/ |,/g, "+");
                   var s = document.createElement('script');     
                   s.src = 'http://open.mapquestapi.com/nominatim/v1/search?q='+strV+'&json_callback=cbv&format=json&polygon=1&addressdetails=1';
                document.getElementsByTagName('head')[0].appendChild(s);
                }

            }

The data retrieved from the request is handled by the cbv function which takes in an argument.

 function cbv(json) 
            {
                v_lat[0] = json[0].lat;
                v_lng[0] = json[0].lon; 
             }

However, I require the ability to pass an additional parameter to the cbv function from the fieldVia_changed function in order to properly process the information. The definition of the cbv function would need to be adjusted to include another argument, such as function cbv(json,a). Despite my thorough search efforts, I have been unable to find a solution for this issue. Is it feasible to achieve?

javascript json jsonp

Answer 1

Answer №1

When working with a JSONP system on the server side, passing additional arguments may not be an option. One way to address this is by utilizing the value of a in the callback function name and creating a dynamic function that acts as a mediator between the cbv() function, enabling the passing of a as a second argument.

function fieldVia_changed(a) {
    if (document.getElementsByName("via" + a)[0].value.trim().length != 0) {

        // dynamically create the function
        window['cbv_' + a] = function (json) {
            cbv(json, a);
        };

        var via = document.getElementsByName("via" + a)[0].value;
        var strV = via.replace(/ |,/g, "+");
        var s = document.createElement('script');
        // call the function cbv_x
        s.src = 'http://open.mapquestapi.com/nominatim/v1/search?q=' + strV + '&json_callback=cbv_' + a + '&format=json&polygon=1&addressdetails=1';
        document.getElementsByTagName('head')[0].appendChild(s);
    }
}

function cbv(json, a) {
    v_lat[0] = json[0].lat;
    v_lng[0] = json[0].lon;
    console.log(a);
}

It's important to note that using a as part of the function name works well when it functions as a short identifier. However, if a originates from user input, it may not be ideal for use in the function name. Nevertheless, since you are using it in the name attributes, it should suffice for its intended purpose.

Answer 2

When working with a JSONP system on the server side, passing additional arguments may not be an option. One way to address this is by utilizing the value of a in the callback function name and creating a dynamic function that acts as a mediator between the cbv() function, enabling the passing of a as a second argument.

function fieldVia_changed(a) {
    if (document.getElementsByName("via" + a)[0].value.trim().length != 0) {

        // dynamically create the function
        window['cbv_' + a] = function (json) {
            cbv(json, a);
        };

        var via = document.getElementsByName("via" + a)[0].value;
        var strV = via.replace(/ |,/g, "+");
        var s = document.createElement('script');
        // call the function cbv_x
        s.src = 'http://open.mapquestapi.com/nominatim/v1/search?q=' + strV + '&json_callback=cbv_' + a + '&format=json&polygon=1&addressdetails=1';
        document.getElementsByTagName('head')[0].appendChild(s);
    }
}

function cbv(json, a) {
    v_lat[0] = json[0].lat;
    v_lng[0] = json[0].lon;
    console.log(a);
}

It's important to note that using a as part of the function name works well when it functions as a short identifier. However, if a originates from user input, it may not be ideal for use in the function name. Nevertheless, since you are using it in the name attributes, it should suffice for its intended purpose.

Sending arguments to the json_callback function

Answer №1

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