chrome.runtime.sendMessage the parameter message, does support function type?

Question

var msg = { name: '', type: 'xhr', success: function(){}, args: {
url: 'exp.com', type: 'GET', dataType: 'html', success: function(){}, error: function(){console.log('failed') } };

chrome.runtime.sendMessage(msg, function(response){
    console.log(response);
});

i try to make a callback function, like success: function(){}, error(){}, but is does not work, why ?

when i use chrome.runtime.onMessage.addListener(function(message, sender, sendResponse){ console.log(message) }); but can not receive success: function(){}, error:function(){} ?

Answer 1

No, sendMessage does not support sending functions. sendMessage operates by serializing the object to a JSON string before sending the message. JSON does not support functions (for several reasons), and any function objects inside the message will be dropped. For example, test out JSON.stringify({ success: function() {} }): you get the result "{}", because keys whose values are functions get dropped.

Instead, you'll either need to:

1. Pass some function parameters in the message and have the receiver build a new function. For example, pass success: { action: "display", header: "Here are your results..." } and then have the receiver use those parameters to build a new function that performs the display action with the given header value.

2. Turn the function into a string before transmission, and then eval the function string to rebuild the function upon receipt. This is a bit of a nasty hack, and will drop any outer scope the function previously had access to, but it will work. Note that you'll need to wrap the function expression in parentheses to have eval parse it:

   eval( "(" + functionString + ")" );