How to call a javascript function from a JSON string?

15,746

Solution 1

This should work:

function(data) {
  if(data.HasCallback) {
    eval(data.Callback);
  }
}

Edit: Didn't look quite carefully enough. If you're indeed getting the function() { ... } text, then you need to eval(data.Callback + "()").

Solution 2

eval("(" + functionDeclarationAsString + ")()");

while functionDeclaractionAsString would be something in the form of function(){ alert('I came from the server'); }

EDIT

The notation (functionReference)(); is used to call a reference to a function. The following would be valid:

(function() { alert('it works'); })();

The following also would be valid:

var my_function = function(param) { alert(param); };
(my_function)('this is a parameter');

Solution 3

It's a better idea to keep code and data separate. To use your example, why not have JSON like this:

{
    "Message": "I came from the server"
}

And in your JavaScript:

$.post('MyApp/GetPostResult.json', function(data) {
    if (data.Message) {
        alert(data.Message);
    }
});
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smartcaveman
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Updated on June 05, 2022

Comments

  • smartcaveman
    smartcaveman almost 2 years

    If I do an AJAX post with jQuery that looks like

     $.post('MyApp/GetPostResult.json', function(data) {
        // what goes here?
     });
    

    and the result looks like

    {
        "HasCallback": true,
        "Callback": "function(){ alert('I came from the server'); }"
    };
    

    Then how do I call the Callback function? Can I just write if(data.HasCallback){data.Callback();} ?