Current File : /home/jalalj2hb/www/wp-content/themes/generatepress/js/back-to-top.js
( function() {
'use strict';
// Feature Test
if ( 'querySelector' in document && 'addEventListener' in window ) {
var goTopBtn = document.querySelector( '.generate-back-to-top' );
var trackScroll = function() {
var scrolled = window.pageYOffset;
var coords = goTopBtn.getAttribute( 'data-start-scroll' ) ;
if ( scrolled > coords ) {
goTopBtn.style.opacity = '1';
goTopBtn.style.visibility = 'visible';
}
if (scrolled < coords) {
goTopBtn.style.opacity = '0';
goTopBtn.style.visibility = 'hidden';
}
};
// Function to animate the scroll
var smoothScroll = function (anchor, duration) {
// Calculate how far and how fast to scroll
var startLocation = window.pageYOffset;
var endLocation = document.body.offsetTop;
var distance = endLocation - startLocation;
var increments = distance/(duration/16);
var stopAnimation;
// Scroll the page by an increment, and check if it's time to stop
var animateScroll = function () {
window.scrollBy(0, increments);
stopAnimation();
};
// Stop animation when you reach the anchor OR the top of the page
stopAnimation = function () {
var travelled = window.pageYOffset;
if ( travelled <= (endLocation || 0) ) {
clearInterval(runAnimation);
}
};
// Loop the animation function
var runAnimation = setInterval(animateScroll, 16);
};
if ( goTopBtn ) {
// Show the button when scrolling down.
window.addEventListener( 'scroll', trackScroll );
// Scroll back to top when clicked.
goTopBtn.addEventListener( 'click', function( e ) {
e.preventDefault();
smoothScroll( document.body, goTopBtn.getAttribute( 'data-scroll-speed' ) || 400 );
}, false );
}
}
} )();
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