将Javascript中的值返回到C＃HTML文件

Question

Here is my issue, I have a javascript function in a .js file that performs some actions, gathers information, and uses a callback. The callback function is also a javascript function but resides in a .cshtml file. I am have difficulties returning a value from my .js javascript function to my .cshml javascript callback function.

Here is a little sample code...

my .js function which I would like to return a value from:

function returnVal(itemID, onCompleteCallback) {
//get vals from DB
onCompleteCallback();
}

my .cshtml script that calls the previous function and I need to get the returned value is a button click even:

updateBtn.onclick = function(e) {
if(action==1) {
    returnVal(itemID, OnCompleted);
}

I have tried 2 methods, neither has worked. I have tried returning a value within the "returnVal" function which doesn't seem to results in anything being returned. I have also tried passing a variable as type var and setting it within the returnVal function, it was my understanding that primitives are passed by value (and thus this wouldn't work) but objects are passed by reference and so I thought this would work. At any rate, neither was successful. Bellow are examples of how I have tried the aforementioned 2 methods:

Method 1:

function returnVal(itemID, onCompleteCallback) {
//get vals from DB
onCompleteCallback();
return x;
}

updateBtn.onclick = function(e) {
    if(action==1) {
        x = returnVal(itemID, OnCompleted);
    }
}

Method 2:

   function returnVal(x, itemID, onCompleteCallback) {
    //get vals from DB
    onCompleteCallback();
    }

updateBtn.onclick = function(e) {
    if(action==1) {
        var x;
        returnVal(x, itemID, OnCompleted);
    }
}

In both cases 'x' is not set. I hope I have provided enough details, any help would be greatly appreciated.

Answer 1

I think you want something like

function returnVal(itemId, onComplete){
    var data = getValueFromDatabase();
    onComplete(data);
}

updateBtn.onclick = function(e) {
    if(action==1) {
        returnVal(itemID, function(data){
            // Do something with returned value i.e. 'data'
        });
    }
}