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How to Evaluate Returned JavaScript Functions from Ajax Responses?

Linda HamiltonOriginal: 2024-10-22 12:44:03169browse

Integrating Ajax-Returned JavaScript Functions

The challenge arises when an Ajax response delivers a script block containing a JavaScript function. Execution of this function becomes necessary to trigger specific actions.

Solution: Evaluating the Function Code

Despite its placement within a

element, the browser is unaware of the new function's existence unless the declaration code is explicitly executed. To achieve this, the function's code must be evaluated using eval(), officially declaring the function and making it accessible throughout the page's lifetime.

Consider the following simplified example:

<code class="html"><script>
  var newFunc = '<script>function go() { alert("Hello!") }</script>';
  var e = document.getElementById('myElement');
  e.innerHTML = newFunc;
  eval(document.getElementById('newFunc').innerHTML);
</script></code>

In this scenario, Ajax is not used, but the concept remains the same. The script block is dynamically inserted into a

before eval() is used to execute the function declaration.

Additional Considerations

It's worth noting that this approach may not be optimal in all situations. Repeated Ajax invocations or concerns over function persistence within varying contexts may warrant alternative design solutions such as:

Exposing the function in a separate JavaScript file
Employing the Prototype approach outlined by krosenvold (cross-browser compatibility, tested functionality)

Ultimately, the best solution depends on the specific requirements and context of the application.

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