聚焦時將類添加到輸入，并在未聚焦時將其洗掉-有解無憂

我正在嘗試將類“.contact__form-input--focused”添加到以表單為焦點的輸入中。

我正在嘗試為每個輸入添加一個事件偵聽器，然后如果該類已經從類串列中洗掉該類。

//INPUT ANIMATION
const input = document.querySelectorAll("contact__form-input");

function addClass(input) {
  input.classList.add("contact__form-input--focused");
}

function removeClass(input) {
  input.classList.remove("contact__form-input--focused");
}

for (let i = 0; i < input.length; i  ) {
  if (item[i].classList.contains("contact__form-input--focused")) {
    item.addEventListener("focus", addClass(input[i]));
  } else {
    item.addEventListener("blur", removeClass(input[i]));
  }
}

.contact__form {
  display: flex;
  flex-direction: column;
}

.contact__form-input {
  border: none;
  border-bottom: .1rem solid rgba(0, 0, 0, .12);
  font-size: var(--medium-font-size);
  margin: 0;
  padding: 4px 0;
  width: 100%;
  background: 0 0;
  text-align: left;
  color: inherit;
}

.contact__form-input--focused {
  /*some animations here*/
}

<form class="contact__form" method="POST">
  <label class="contact__form-label">
            <span>Name</span>
            <input class="contact__form-input" name="Name" type="text" autocomplete="name" required>
          </label>
  <label class="contact__form-label">
            <span>Phone number</span>
            <input class="contact__form-input" name="Phone number" type="tel" autocomplete="tel" required>
          </label>
  <label class="contact__form-label">
            <span>Message</span>
            <input class="contact__form-input" type="text" required>
          </label>
  <button class="contact__form-button">Send</button>
</form>

uj5u.com熱心網友回復：

如果你像這樣使用 JS 而不僅僅是:focus你的偽代碼可以通過

const inputs = document.querySelectorAll("contact__form-input");
inputs.forEach(input => {
    input.addEventListener("focus", function(){
        this.classList.add("contact__form-input--focused");
    });
    input.addEventListener("blur", function(){
        this.classList.remove("contact__form-input--focused");
    });
});

或者如果你想切換課程

const inputs = document.querySelectorAll("contact__form-input");
function switchInputClasses(){
    this.classList.toggle("contact__form-input");
    this.classList.toggle("contact__form-input--focused");
}
inputs.forEach(input => {
    input.addEventListener("focus", switchInputClasses);
    input.addEventListener("blur", switchInputClasses);
});

函式宣告而不是函式宣告的原因()=>{}是因為后者將保留范圍并this正確設定關鍵字您需要更改范圍，想到它的最好方法EventListner是apply()在元素上呼叫通過

偽方法只是將您的 CSS 更改為

.contact__form {
  display: flex;
  flex-direction: column;
}

.contact__form-input {
  border: none;
  border-bottom: .1rem solid rgba(0, 0, 0, .12);
  font-size: var(--medium-font-size);
  margin: 0;
  padding: 4px 0;
  width: 100%;
  background: 0 0;
  text-align: left;
  color: inherit;
}

.contact__form-input:focus {
  /*some animations here*/
}

uj5u.com熱心網友回復：

1)你沒有得到 HTML 元素，因為它contact__form-input是一個類，你必須通過在 className 之前附加來告訴querySelectorAll你正在查找其類是contact__form-input的所有元素.

const inputs = document.querySelectorAll( ".contact__form-input" );

2）您應該添加eventListener上focus或blur為：

inputs.forEach(input => {
  input.addEventListener("focus", () => addClass(input))
  input.addEventListener("blur", () => removeClass(input))
})

NOTE: For demo purpose I've added thick red border

//INPUT ANIMATION
const inputs = document.querySelectorAll(".contact__form-input");

function addClass(input) {
  input.classList.add("contact__form-input--focused");
}

function removeClass(input) {
  input.classList.remove("contact__form-input--focused");
}

console.log(inputs)

inputs.forEach(input => {
  input.addEventListener("focus", () => addClass(input))
  input.addEventListener("blur", () => removeClass(input))
})

.contact__form {
  display: flex;
  flex-direction: column;
}

.contact__form-input {
  border: none;
  border-bottom: .1rem solid rgba(0, 0, 0, .12);
  font-size: var(--medium-font-size);
  margin: 0;
  padding: 4px 0;
  width: 100%;
  background: 0 0;
  text-align: left;
  color: inherit;
}

.contact__form-input--focused {
  /*some animations here*/
  border: 5px solid red;
}

<form class="contact__form" method="POST">
  <label class="contact__form-label">
            <span>Name</span>
            <input class="contact__form-input" name="Name" type="text" autocomplete="name" required>
          </label>
  <label class="contact__form-label">
            <span>Phone number</span>
            <input class="contact__form-input" name="Phone number" type="tel" autocomplete="tel" required>
          </label>
  <label class="contact__form-label">
            <span>Message</span>
            <input class="contact__form-input" type="text" required>
          </label>
  <button class="contact__form-button">Send</button>
</form>

uj5u.com熱心網友回復：

你不需要if宣告。只需將兩個事件偵聽器添加到所有輸入即可。

的第二個引數addEventListener()必須是一個函式。您立即呼叫該函式，而不是在事件發生時呼叫。

//INPUT ANIMATION
const input = document.querySelectorAll(".contact__form-input");

function addClass(input) {
  input.classList.add("contact__form-input--focused");
}

function removeClass(input) {
  input.classList.remove("contact__form-input--focused");
}

for (let i = 0; i < input.length; i  ) {
  let item = input[i];
  item.addEventListener("focus", () => addClass(item));
  item.addEventListener("blur", () => removeClass(item));
}

.contact__form {
  display: flex;
  flex-direction: column;
}

.contact__form-input {
  border: none;
  border-bottom: .1rem solid rgba(0, 0, 0, .12);
  font-size: var(--medium-font-size);
  margin: 0;
  padding: 4px 0;
  width: 100%;
  background: 0 0;
  text-align: left;
  color: inherit;
}

.contact__form-input--focused {
  background-color: yellow;
}

<form class="contact__form" method="POST">
  <label class="contact__form-label">
            <span>Name</span>
            <input class="contact__form-input" name="Name" type="text" autocomplete="name" required>
          </label>
  <label class="contact__form-label">
            <span>Phone number</span>
            <input class="contact__form-input" name="Phone number" type="tel" autocomplete="tel" required>
          </label>
  <label class="contact__form-label">
            <span>Message</span>
            <input class="contact__form-input" type="text" required>
          </label>
  <button class="contact__form-button">Send</button>
</form>

uj5u.com熱心網友回復：

<style type="text/css">
    .contact__form {
        display: flex;
        flex-direction: column;
    }
    .contact__form-input {
        border: none;
        border-bottom: .1rem solid rgba(0, 0, 0, .12);
        font-size: var(--medium-font-size);
        margin: 0;
        padding: 4px 0;
        width: 100%;
        background: 0 0;
        text-align: left;
        color: inherit;
    }

    .contact__form-input--focused {
        /*some animations here*/
    }
</style>

<form class="contact__form" method="POST">
    <label class="contact__form-label">
        <span>Name</span>
        <input class="contact__form-input" name="Name" type="text" autocomplete="name">
    </label>
    <label class="contact__form-label">
        <span>Phone number</span>
        <input class="contact__form-input" name="Phone" type="tel" autocomplete="tel" required>
    </label>
    <label class="contact__form-label">
        <span>Message</span>
        <input class="contact__form-input" name="Text" type="Text" required>
    </label>
    <button class="contact__form-button">Send</button>
</form>

<script>
    const inputName = document.querySelector("input[name=Name]");
    const inputPhone = document.querySelector("input[name=Phone]");
    const inputText = document.querySelector("input[name=Text]");
    inputName.addEventListener("focus", function() {
        if(inputName.classList.contains("contact__form-input--focused"))
            inputName.classList.remove("contact__form-input--focused");
        else
            inputName.classList.add("contact__form-input--focused");
    });
    inputPhone.addEventListener("focus", function() {
        if(inputPhone.classList.contains("contact__form-input--focused"))
            inputPhone.classList.remove("contact__form-input--focused");
        else
            inputPhone.classList.add("contact__form-input--focused");
    });
    inputText.addEventListener("focus", function() {
        if(inputText.classList.contains("contact__form-input--focused"))
            inputText.classList.remove("contact__form-input--focused");
        else
            inputText.classList.add("contact__form-input--focused");
    });
</script>

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標籤：javascript html css 数组

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