[英]Slider- Previous button hides first slide instead of previous slide
我創建了一些CSS和JavaScript,將WordPress的本機庫變成了幻燈片。 對於每個畫廊,我都有下一個和上一個按鈕,這些按鈕在單擊時顯示每個幻燈片。
問題是單擊以顯示上一張幻燈片時,它僅顯示第一張幻燈片。 我認為這是因為位於click函數之外的初始計數器被設置為0。是否有任何方法可以跟蹤每個函數之間計數器在哪個幻燈片上滑動,或者可以自行調整函數?
這是JavaScript:
function() {
...
var gallery = document.querySelectorAll('.single.slider .gallery');
var galleries = [ document.querySelector('.single.slider #gallery-1'),
document.querySelector('.single.slider #gallery-2') ];
var slides = [ document.querySelectorAll('.single.slider #gallery-1 .gallery-item'),
document.querySelectorAll('.single.slider #gallery-2 .gallery-item') ];
var slides1Count = 0;
var slides2Count = 0;
function hideFirstSlide() {
// slides[0] = first location of the array in the slides variable, slides[1] = second, etc.
// slides[0][0] = first slide inside of the first array
for (var iGal = 0, len = galleries.length; iGal < len; iGal++) {
//console.log('number of galleries: ' + iGal);
for (var jSlide = 0, len = slides.length; jSlide < len; jSlide++) {
//console.log('number of slides within gallery: ' + slides[jSlide].length); // for debugging
//console.log(slides[0][0]); // for debugging
// We must loop over each slide when using querySelectorAll
for (var kEachSlide = 0; kEachSlide < slides[jSlide].length; kEachSlide++) {
//console.log(slides[jSlide].length); // Number of slides within current selected query
// Hide all slides within each slides array;
if (slides[0][kEachSlide]) {
slides[0][kEachSlide].classList.add('hide');
}
if (slides[1][kEachSlide]) {
slides[1][kEachSlide].classList.add('hide');
}
// Show first slide within each slides array
if (slides[0][0]) {
slides[0][0].classList.remove('hide');
}
if (slides[1][0]) {
slides[1][0].classList.remove('hide');
}
}
}
}
}
window.onload = hideFirstSlide();
for (var i = 0, len = gallery.length; i < len; i++) {
// Add slider controls to each gallery
gallery[i].insertAdjacentHTML('afterend', '<div class="slider-button-panel"><button class="slider-previous"></button><button class="slider-startshow">Start Slideshow</button><button class="slider-next"></button></div>');
//console.log(gallery.length);
}
var sliderButtonPrevious = document.querySelectorAll('.single.slider .slider-previous');
var sliderButtonNext = document.querySelectorAll('.single.slider .slider-next');
var sliderNext = [ document.querySelector('.single.slider #gallery-1 + .slider-button-panel .slider-next'),
document.querySelector('.single.slider #gallery-2 + .slider-button-panel .slider-next') ];
var sliderPrevious = [ document.querySelector('.single.slider #gallery-1 + .slider-button-panel .slider-previous'),
document.querySelector('.single.slider #gallery-2 + .slider-button-panel .slider-previous') ];
// Show each subsequent slide one at a time by clicking the next and previous buttons
// checking if each button exists on the page first
if (sliderNext[0]) {
sliderNext[0].addEventListener('click', showNext(slides[0], slides1Count));
}
if (sliderNext[1]) {
sliderNext[1].addEventListener('click', showNext(slides[1], slides2Count));
}
if (sliderPrevious[0]) {
sliderPrevious[0].addEventListener('click', showPrevious(slides[0], slides1Count));
}
if (sliderPrevious[1]) {
sliderPrevious[1].addEventListener('click', showPrevious(slides[1], slides2Count));
}
// Next slide function
function showNext(obj, counter) {
return function() {
obj[counter].classList.add('hide');
counter++;
if (counter === obj.length) {
counter = obj.length - 1;
}
obj[counter].classList.remove('hide');
//console.log(counter);
}
}
// Previous slide function
function showPrevious(obj, counter) {
return function() {
obj[counter].classList.add('hide');
counter--;
if (counter === -1) {
counter = 0;
}
obj[counter].classList.remove('hide');
console.log(counter);
}
}
)();
以下是相關的HTML和CSS:
<div id="gallery-1" class="gallery galleryid-555 gallery-columns-3 gallery-size-large">
<figure class="gallery-item">
<div class="gallery-icon landscape">
<a href="#"><img src= ... /></a>
</div>
<figcaption class="wp-caption-text gallery-caption" ...>A Caption</figcaption>
</figure>
<figure class="gallery-item hide">
<div class="gallery-icon landscape">
<a href="#"><img src= ... /></a>
</div>
</figure>
...
each slide thereafter has .hide class attached
</div>
<div id="gallery-2" class="gallery galleryid-555 gallery-columns-3 gallery-size-large">
<figure class="gallery-item">
<div class="gallery-icon landscape">
<a href="#"><img src= ... /></a>
</div>
</figure>
<figure class="gallery-item hide">
<div class="gallery-icon landscape">
<a href="#"><img src= ... /></a>
</div>
</figure>
...
</div>
...
.gallery-item {
margin: 0 auto;
}
.single.slider .gallery {
position: relative;
min-width: 100%;
}
.single.slider .gallery-item {
max-width: none;
position: absolute;
top: 0;
width: 100%;
}
.hide {
display: none;
}
我也在這里的JSFiddle中包括一個精簡版: https ://jsfiddle.net/jgpws/fkbrbkLa/。
謝謝。
好的,經過幾個月的研究並閱讀了一些教程和其他SO帖子之后,我終於找到了解決方案。
我將增加或減少幻燈片(隱藏和顯示)的每個單獨功能更改為只處理向上和向下計數的功能。 此函數返回向上或向下計數的兩個對象。 然后,修改了單擊處理程序以添加和刪除hide類。 然后,在點擊處理程序中,需要再次調用count函數。 該部分只能通過反復試驗才能起作用。 因此,我只知道它有效,但不知道為什么。 也許它在隱藏/顯示后重置了節點列表的位置?
另外,例如,當我單擊前進然后立即單擊后退時,我必須單擊兩次。 第二次單擊,幻燈片將返回。
由於此解決方案已經足夠接近我所尋找的內容,因此我可以接受。 這是更新的代碼:
function() {
...
var slides = [ document.querySelectorAll('.single.slider #gallery-1 .gallery-item'),
document.querySelectorAll('.single.slider #gallery-2 .gallery-item') ];
//var slides1Count = 0;
//var slides2Count = 0;
...
// Next slide function
function showSlide(obj) {
var counter = 0;
return {
showNext: function() {
counter++;
if (counter === obj.length) {
counter = obj.length - 1;
}
console.log('Next slide: ' + counter);
return counter;
},
showPrevious: function() {
counter--;
if (counter < 0) {
counter = 0;
}
console.log('Previous slide: ' + counter);
return counter;
}
}
}
// Show each subsequent slide one at a time by clicking the next and previous buttons
// checking if each button exists on the page first
function addClickEvents() {
var currentSlide1 = showSlide(slides[0]);
var currentSlide2 = showSlide(slides[1]);
if (sliderNext[0]) {
sliderNext[0].addEventListener('click', function() {
slides[0][currentSlide1.showPrevious()].classList.add('hide');
slides[0][currentSlide1.showNext()].classList.remove('hide');
slides[0][currentSlide1.showNext()];
});
}
if (sliderNext[1]) {
sliderNext[1].addEventListener('click', function () {
slides[1][currentSlide2.showPrevious()].classList.add('hide');
slides[1][currentSlide2.showNext()].classList.remove('hide');
slides[1][currentSlide2.showNext()];
});
}
if (sliderPrevious[0]) {
sliderPrevious[0].addEventListener('click', function() {
slides[0][currentSlide1.showPrevious()].classList.remove('hide');
slides[0][currentSlide1.showNext()].classList.add('hide');
slides[0][currentSlide1.showPrevious()];
});
}
if (sliderPrevious[1]) {
sliderPrevious[1].addEventListener('click', function () {
slides[1][currentSlide2.showPrevious()].classList.remove('hide');
slides[1][currentSlide2.showNext()].classList.add('hide');
slides[1][currentSlide2.showPrevious()];
});
}
}
window.onload = addClickEvents();
)();
可以更改某些函數名稱以更好地描述它們的功能,但這對我有用。
文章《 輕松理解JavaScript閉包 》中的代碼示例對我有很大幫助,因為對文章中某些代碼的改編幫助我弄清楚了可以在每個按鈕的click事件之間共享的計數器。
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