JavaScript 在用户填写或不填写文本字段时更改文本字段

Question

我需要一项作业的帮助：当用户填写文本字段并且文本字段失去焦点时，用复选标记将文本字段设为绿色。 您可以使用 FontAwesome 中的复选标记。 当用户未填写文本字段但移除焦点时，将文本字段设为红色并带有叉号 我需要 javascript/dom 代码来完成此任务。 我试过这段代码但不起作用：

    let fields = document.getElementsByTagName("input");
const checkFields = function () {
    for (let i = 0; i < fields.length; i++) {
        if (fields[i].value == "") {
          fields[i].style.backgroundColor = "red";
        } else {
          fields[i].style.backgroundColor = "green";
        }
      }
}
fields.addEventListener('change', checkFields)



          <div class="controls">
            <input
              autofocus=""
              class="input-xlarge"
              id="company"
              name="company"
              placeholder="Company name"
              type="text"
              value=""
            />
          </div>
        </section>

        <section class="control-group">
          <label class="control-label" for="fname">Name</label>

          <div class="controls two-col">
            <input
              class="input-medium"
              id="fname"
              name="fname"
              placeholder="First name"
              type="text"
              value=""
            />
          </div>

          <div class="controls two-col">
            <input
              class="input-medium"
              id="lname"
              name="lname"
              placeholder="Last name"
              type="text"
              value=""
            />
          </div>
        </section>

        <section class="control-group">
          <label class="control-label" for="email">Email</label>

          <div class="controls">
            <input
              class="input-xlarge"
              id="email"
              name="email"
              placeholder="Email"
              type="email"
              value=""
            />
          </div>
        </section>

Answer 1

这是您的解决方案：

 // Select Each Input document.querySelectorAll('input').forEach((inp) => { // Remove whitespace from value and check it // Add eventlistener on each input inp.addEventListener('change', () => { let value = inp.value.split(' ').join('') // Do something with value; if (value == "") { inp.style.backgroundColor = "red"; } else { inp.style.backgroundColor = "green"; } }) })

 <section> <div class="controls"> <input autofocus="" class="input-xlarge" id="company" name="company" placeholder="Company name" type="text" value="" /> </div> </section> <section class="control-group"> <label class="control-label" for="fname">Name</label> <div class="controls two-col"> <input class="input-medium" id="fname" name="fname" placeholder="First name" type="text" value="" /> </div> <div class="controls two-col"> <input class="input-medium" id="lname" name="lname" placeholder="Last name" type="text" value="" /> </div> </section> <section class="control-group"> <label class="control-label" for="email">Email</label> <div class="controls"> <input class="input-xlarge" id="email" name="email" placeholder="Email" type="email" value="" /> </div> </section>

Answer 2

您可以使用“focusout”事件，如果我正确理解您的问题，我相信这将是更好的选择。

const ips = document.querySelectorAll("input")

ips.forEach(ip=>ip.addEventListener("focusout", ()=>{
    const text = ip.value
    if (text === "") ip.style.border= "1px solid red"
    else ip.style.border = "1px solid green"
 })
)