How Can I Trigger JavaScript Functions from HTML Buttons?

How to Invoke JavaScript Functions Using HTML Buttons

To interface with JavaScript code, HTML buttons offer a convenient solution. When a button is clicked, the browser executes the associated JavaScript function.

HTML-Defined Event Handling

One approach is to specify the function call directly within the HTML code:

<input type="button" value="Capacity Chart" onclick="CapacityChart();">

DOM Event Property Manipulation

Alternatively, you can assign the event handler to the DOM property using JavaScript:

document.getElementById("clickMe").onclick = function () { /* ... */ };

Event Listener Attachment

Another option is to attach a function to the event listener:

var el = document.getElementById("clickMe");
el.addEventListener("click", function () { /* ... */ }, false);

Troubleshooting Button Invocation

Consider the following when debugging button event invocation:

• Ensure the CapacityChart() function is defined correctly.
• Check for errors in the script itself.
• Consider modifying the document.write() line to:

CapacityWindow.document.open("text/html");
CapacityWindow.document.write(s);
CapacityWindow.document.close();

Cross-Browser Compatibility

To support multiple browsers, replace document.all references with document.getElementById.

Additional Notes

• The three event handling methods mentioned are not mutually exclusive.
• The first is discouraged as it's not XHTML-compliant.
• The second and third methods allow for anonymous functions and post-element-parsing event definition.
• The third method permits attaching multiple functions to the same event handler.

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