Uncaught TypeError


Joined
Mar 25, 2021
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Hi, the TriggerBttn line towards the end (line 39 and it is referencing the last line) is giving an Uncaught TypeError: triggerBttn is null error. Nothing seems to be broken, but am interested in how to resolve this. It is possible that this relates to a responsive hamburger icon and since the page is a one pager there is no navigation so no responsive menu is utilized. Still digging but that is my thought at the moment.

JavaScript:
(function() {
    var triggerBttn = document.getElementById( 'trigger-overlay' ),
        overlay = document.querySelector( 'div.overlay' ),
        closeBttn = overlay.querySelector( 'button.overlay-close' );
        transEndEventNames = {
            'WebkitTransition': 'webkitTransitionEnd',
            'MozTransition': 'transitionend',
            'OTransition': 'oTransitionEnd',
            'msTransition': 'MSTransitionEnd',
            'transition': 'transitionend'
        },
        transEndEventName = transEndEventNames[ Modernizr.prefixed( 'transition' ) ],
        support = { transitions : Modernizr.csstransitions };

    function toggleOverlay() {
        if( classie.has( overlay, 'open' ) ) {
            classie.remove( overlay, 'open' );
            classie.add( overlay, 'close' );
            var onEndTransitionFn = function( ev ) {
                if( support.transitions ) {
                    if( ev.propertyName !== 'visibility' ) return;
                    this.removeEventListener( transEndEventName, onEndTransitionFn );
                }
                classie.remove( overlay, 'close' );
            };
            if( support.transitions ) {
                overlay.addEventListener( transEndEventName, onEndTransitionFn );
            }
            else {
                onEndTransitionFn();
            }
        }
        else if( !classie.has( overlay, 'close' ) ) {
            classie.add( overlay, 'open' );
        }
        event.preventDefault();
    }

    triggerBttn.addEventListener( 'click', toggleOverlay );
    closeBttn.addEventListener( 'click', toggleOverlay );
})();
 
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Joined
Mar 11, 2022
Messages
82
Reaction score
8
i would assume so. What does console.log(triggerBttn) say? If there is no button element with a overlay-close class, the addEventListsner of course shout an error. Same with closeBttn.

I mean, check if those elements exists.
Code:
(function() {
var triggerBttn = document.getElementById( 'trigger-overlay' ),
overlay = document.querySelector( 'div.overlay' ),
closeBttn = overlay.querySelector( 'button.overlay-close' );
if(triggerBttn && overlay && closeBttn){
transEndEventNames = {
'WebkitTransition': 'webkitTransitionEnd',
'MozTransition': 'transitionend',
'OTransition': 'oTransitionEnd',
'msTransition': 'MSTransitionEnd',
'transition': 'transitionend'
},
transEndEventName = transEndEventNames[ Modernizr.prefixed( 'transition' ) ],
support = { transitions : Modernizr.csstransitions };

function toggleOverlay() {
if( classie.has( overlay, 'open' ) ) {
classie.remove( overlay, 'open' );
classie.add( overlay, 'close' );
var onEndTransitionFn = function( ev ) {
if( support.transitions ) {
if( ev.propertyName !== 'visibility' ) return;
this.removeEventListener( transEndEventName, onEndTransitionFn );
}
classie.remove( overlay, 'close' );
};
if( support.transitions ) {
overlay.addEventListener( transEndEventName, onEndTransitionFn );
}
else {
onEndTransitionFn();
}
}
else if( !classie.has( overlay, 'close' ) ) {
classie.add( overlay, 'open' );
}
event.preventDefault();
}

triggerBttn.addEventListener( 'click', toggleOverlay );
closeBttn.addEventListener( 'click', toggleOverlay );
}})();
 

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