javascript - 在 for 循环中将变量名称与迭代器索引连接起来

Question

我试图在 javascript 中创建一组按钮，使 slider 根据我单击的按钮交换图像。

我想到了这个丑陋的冗余代码:

var changer1 = document.getElementById("changer1");
var changer2 = document.getElementById("changer2");
var changer3 = document.getElementById("changer3");

var r = document.getElementsByClassName('carousel-item');

changer1.addEventListener('click', function() {
    for (let i = 0; i < r.length; i++) {
        r[i].classList.remove('active')
    }
    r[0].classList.add('active')
});

changer2.addEventListener('click', function() {
    for (let i = 0; i < r.length; i++) {
        r[i].classList.remove('active')
    }
    r[1].classList.add('active')
});

changer3.addEventListener('click', function() {
    for (let i = 0; i < r.length; i++) {
        r[i].classList.remove('active')
    }
    r[2].classList.add('active')
});

它成功了，但我知道可以优化冗余代码，所以我尝试了这个:

var changersArray = document.getElementsByClassName('changers');

for (let i = 0; i < 3; i++) {  
    changer[i].addEventListener('click', function() {
        for (let i = 0; i < r.length; i++) {
            r[i].classList.remove('active')
        }
        r[0].classList.add('active')
    });
}

这是 HTML:

<section class="container-fluid sectionFive">
    <div class="row title_image">
        <div class="col-sm-12">
            <h1 class="wow flipInY delay-1s slow">Testimonials</h1>
        </div>
    </div>

    <div class="row">
        <div class="col-sm-2"></div>
        <div class="col-sm-8 fetchDiv">

            <div id="carouselExampleControls" class="carousel slide wow
                    fadeIn" data-ride="carousel">
                <div class="carousel-inner">
                    <div class="carousel-item active">
                        <img class="mt-2 rounded-circle people" src="images/person_3.jpg" alt="">
                        <p class="frase"></p>
                        <p class="author"></p>

                    </div>
                    <div class="carousel-item">
                        <img class="mt-2 rounded-circle people" src="images/person_2.jpg" alt="">
                        <p class="frase"></p>
                        <p class="author"></p>

                    </div>
                    <div class="carousel-item">
                        <img class="mt-2 rounded-circle people" src="images/person_1.jpg" alt="">
                        <p class="frase"></p>
                        <p class="author"></p>
                    </div>
                </div>
                <a class="carousel-control-prev" href="#carouselExampleControls" role="button" data-slide="prev">
                    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
                    <span class="sr-only">Previous</span>
                </a>
                <a class="carousel-control-next" href="#carouselExampleControls" role="button" data-slide="next">
                    <span class="carousel-control-next-icon" aria-hidden="true"></span>
                    <span class="sr-only">Next</span>
                </a>
            </div>

        </div>
        <div class="col-sm-2">

        </div>
    </div>
    <div class="row changersRow">
        <button class="changers" id="changer1">1</button><button class="changers" id="changer2">2</button><button class="changers" id="changer3">3</button>

    </div>
</section>

我试图通过在循环中写入 changer[i] 来动态创建 changer1、changer2 和 changer3，但没有成功。

拜托，你能帮我弄清楚为什么它不起作用，我怎样才能让它起作用？

谢谢。

Answer 1

前两个改进来 self 的脑海:

for (let i = 0; i < 3; i++) {  
  changer[i].addEventListener('click', function() {
      for (let j = 0; j < r.length; j++) {
          r[j].classList.remove('active')
      }
      r[i].classList.add('active')
  });
}

注意内部 i 被替换并且 r[0] 更改为使用实际索引