Can't make onclick work on an injected button through content script in chrome extension

Question

I'm developing a chrome extension that injects a button on web page. I'm able to inject the button successfully however i cannot apply a onclick function on it. I wrote button injection code in content.js which is as follows

jQuery('body').append('<button onclick="myFxn();" class="vwsItBtn" style="height: 25px; width: 80px; position: absolute; opacity: 1; font-size: 12px; z-index: 867530999; display: block; padding-right: 4px !important; margin: 0px; border: 2px solid rgb(254, 208, 70); background-color: whitesmoke; border-radius: 4px; font-weight: bolder; text-shadow: #FED046 0px 0px 1px; color: #36373B; text-align-last: end;"><img id="myImgVw" style="width: 15px; display: inline-block; padding: 0px; left: 2px; position: absolute; vertical-align: middle !important; top: 3px;" src="'+chrome.extension.getURL("imgvwextsitbtn.png")+'"/> Schedule</button>');

jQuery(function(){
    function myFxn(){
        alert('This is working!');
    }
})

Now i get an error that myFxn is not defined. Now this function is quite simple but how do i make it work?

This is the first time i'm developing a chrome extension and i'm pretty sure there is some other way of doing it. Please help!!

Answer 1

The problem is because the myFxn() function is declared within the scope of the jQuery document.ready handler, whereas it needs to be global for the on* attribute to be able to access it. Try this:

jQuery('body').append('<button onclick="myFxn();" class="vwsItBtn" style="height: 25px; width: 80px; position: absolute; opacity: 1; font-size: 12px; z-index: 867530999; display: block; padding-right: 4px !important; margin: 0px; border: 2px solid rgb(254, 208, 70); background-color: whitesmoke; border-radius: 4px; font-weight: bolder; text-shadow: #FED046 0px 0px 1px; color: #36373B; text-align-last: end;"><img id="myImgVw" style="width: 15px; display: inline-block; padding: 0px; left: 2px; position: absolute; vertical-align: middle !important; top: 3px;" src="'+chrome.extension.getURL("imgvwextsitbtn.png")+'"/> Schedule</button>');

function myFxn(){
    alert('This is working!');
}

Better yet, put your styling in to separate stylesheets to make your HTML simpler and better separated from the styling and also don't use the outdated on* event attributes and use unobtrusive Javascript to attach your event handlers instead. As you're using jQuery already, here's an example of how to do that:

.vwsItBtn {
    height: 25px; 
    width: 80px; 
    position: absolute; 
    opacity: 1; 
    font-size: 12px; 
    z-index: 867530999; 
    display: block; 
    padding-right: 4px !important; 
    margin: 0px; 
    border: 2px solid rgb(254, 208, 70); 
    background-color: whitesmoke; 
    border-radius: 4px; 
    font-weight: bolder; 
    text-shadow: #FED046 0px 0px 1px; 
    color: #36373B; 
    text-align-last: end;
}
#myImgVw {
    width: 15px; 
    display: inline-block; 
    padding: 0px; left: 2px; 
    position: absolute; 
    vertical-align: middle !important; 
    top: 3px;
}

jQuery(function($) {
    $('body').append('<button class="vwsItBtn"><img id="myImgVw" src="' + chrome.extension.getURL("imgvwextsitbtn.png") + '"/>Schedule</button>');

    $('.vwsItBtn').click(function() {
        alert('This is working!');
    });
});