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returning functions as string in javascript

Answer 1

A:

Use eval() to execute a string as javascript

[EDIT} Sounds then like you need to prototype the form and then in submit call this.validate(). Get a reference to the form object when you create it using javascript and then define your method for validation and assign that to the validate property.

Dave Anderson 2009-07-11 08:06:07

There must be a better way than resorting to "eval()".

Steve Harrison 2009-07-11 08:09:58

undoubtedly but if you have a string value how else can you turn it into something to execute?

Dave Anderson 2009-07-11 08:33:41

@Dave Anderson: You try to avoid ending up with a string value that needs executing... ;)

Steve Harrison 2009-07-11 08:43:01

Answer 2

+5 A:

Rather than outputting the event handler in the HTML attribute, you can output the HTML, get a reference to the form object, then attach an event handler programmatically, like this:

<html>
  <head>
    <script type="text/javascript">
        var my_object = {
            outputForm: function(container) {
                container.innerHTML = 
                    '<form id="a"><input type="submit" value="Validate" /></form>';
                this.createdForm = document.getElementById('a');
                this.createdForm.onsubmit = this.validate;
            },
            validate: function() {
                // use this.createdForm to get at the controls.
                alert("Who dares awake my slumber?");
            }
        };

        function createTheForm() {
            my_object.outputForm(document.getElementById('container'));
        }
    </script>
  </head>
  <body onload="createTheForm()">
    <div id="container"></div>
  </body>
</html>

Jacob 2009-07-11 08:13:47

Answer 3

A:

sorry for posting this as an answer, after registering it wouldn't let me edit my original post as non registered user?

I thought about eval but I'm not sure how to even use it in this situation? I've tried it like so

' onSubmit="return eval(' + this.validate+'();)">';

and some other variations but I get the same error.

I would like to avoid having to manually add the event handling as I would like it to be pretty self contained. I was thinking about setting up a regular function which sits outside of the object and then doing something like

' onSubmit="return my_function(' + this + ');">';

then in my_function do this:

my_function(given){ return given.validate(); }

this seems like an awful hack and I'm not even sure if it will work.

Ori Cohen 2009-07-11 08:17:26

Answer 4

A:

Why are you not just applying it to the element after you add it to the page and using a closure to keep scope?

var myId = "bar" + index;
foo.innerHTML="<form id='" + myId + "'>...</form>";
var that = this;
document.getElementById(myId).onsubmit = function(){ that.validate(this); }

Adding event handlers to the markup is always a bad idea.

epascarello 2009-07-11 13:28:29

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returning functions as string in javascript

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