实现智能搜索提示和输入验证的 Autocomplete 组件教程-php教程-PHP中文网

实现智能搜索提示和输入验证的 autocomplete 组件教程

本文将指导你如何实现一个具备智能搜索提示和输入验证的 Autocomplete 组件。该组件能够在用户输入时提供实时搜索建议，支持在字符串任意位置匹配，并限制用户输入，仅允许选择预设选项，从而增强用户体验和数据准确性。

1. 初始状态显示全部选项

原代码只有在用户输入至少一个字符后才会显示匹配的选项。为了在光标置于空字段时显示所有选项，我们需要修改 input 事件监听器中的逻辑。

inp.addEventListener("input", function(e) {
    var a, b, i, val = this.value;
    closeAllLists();
    // 修改此处：如果输入为空，则显示所有选项
    if (!val) {
      // 显示所有选项的逻辑
      a = document.createElement("DIV");
      a.setAttribute("id", this.id + "autocomplete-list");
      a.setAttribute("class", "autocomplete-items");
      this.parentNode.appendChild(a);
      for (i = 0; i < arr.length; i++) {
          b = document.createElement("DIV");
          b.innerHTML = arr[i];
          b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
          b.addEventListener("click", function(e) {
              inp.value = this.getElementsByTagName("input")[0].value;
              closeAllLists();
          });
          a.appendChild(b);
      }
      return false;
    }
    currentFocus = -1;
    a = document.createElement("DIV");
    a.setAttribute("id", this.id + "autocomplete-list");
    a.setAttribute("class", "autocomplete-items");
    this.parentNode.appendChild(a);
    for (i = 0; i < arr.length; i++) {
      if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {
        b = document.createElement("DIV");
        b.innerHTML = "<strong>" + arr[i].substr(0, val.length) + "</strong>";
        b.innerHTML += arr[i].substr(val.length);
        b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
        b.addEventListener("click", function(e) {
          inp.value = this.getElementsByTagName("input")[0].value;
          closeAllLists();
        });
        a.appendChild(b);
      }
    }
  });

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这段代码在 input 事件监听器中添加了一个条件判断。如果输入框的值为空，则创建一个包含所有选项的列表并显示出来。

2. 实现任意位置匹配

原代码只匹配字符串的开头，要实现任意位置匹配，需要修改 if 条件判断。

inp.addEventListener("input", function(e) {
    var a, b, i, val = this.value;
    closeAllLists();
    if (!val) {
        a = document.createElement("DIV");
        a.setAttribute("id", this.id + "autocomplete-list");
        a.setAttribute("class", "autocomplete-items");
        this.parentNode.appendChild(a);
        for (i = 0; i < arr.length; i++) {
            b = document.createElement("DIV");
            b.innerHTML = arr[i];
            b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
            b.addEventListener("click", function(e) {
                inp.value = this.getElementsByTagName("input")[0].value;
                closeAllLists();
            });
            a.appendChild(b);
        }
        return false;
    }
    currentFocus = -1;
    a = document.createElement("DIV");
    a.setAttribute("id", this.id + "autocomplete-list");
    a.setAttribute("class", "autocomplete-items");
    this.parentNode.appendChild(a);
    for (i = 0; i < arr.length; i++) {
      // 修改此处：使用 indexOf 进行任意位置匹配
      if (arr[i].toUpperCase().indexOf(val.toUpperCase()) > -1) {
        b = document.createElement("DIV");
        // 高亮匹配部分 (可选)
        let index = arr[i].toUpperCase().indexOf(val.toUpperCase());
        let pre = arr[i].substring(0, index);
        let match = arr[i].substring(index, index + val.length);
        let post = arr[i].substring(index + val.length);
        b.innerHTML = pre + "<strong>" + match + "</strong>" + post;
        b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
        b.addEventListener("click", function(e) {
          inp.value = this.getElementsByTagName("input")[0].value;
          closeAllLists();
        });
        a.appendChild(b);
      }
    }
  });

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这里使用了 indexOf 方法来检查字符串中是否包含指定的子字符串。如果 indexOf 返回的值大于 -1，则表示找到了匹配项。同时，为了更好的用户体验，可以对匹配到的字符进行高亮显示。

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3. 限制输入，只允许选择 Autocomplete 值

为了限制用户只能输入 Autocomplete 列表中存在的值，我们需要添加验证逻辑。

// 在 autocomplete 函数外部保存原始数组
var originalArray = [...arr];

inp.addEventListener("blur", function(e) {
    // 验证输入是否在原始数组中
    if (originalArray.indexOf(inp.value) === -1 && inp.value !== "") {
        inp.value = ""; // 清空输入框
        // 或者显示错误提示
        alert("Please select a valid fruit from the list.");
    }
});

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这段代码监听了输入框的 blur 事件（失去焦点时触发）。当输入框失去焦点时，它会检查输入的值是否在原始数组中。如果不在，则清空输入框的值，并可选择显示错误提示。同时，在初始化 autocomplete 函数时，需要将原始数组复制一份保存下来，避免后续修改。

4. 完整代码示例

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
* {
  box-sizing: border-box;
}

body {
  background-color: #f1f1f1;
}

#regForm {
  background-color: #ffffff;
  margin: 10px auto;
  font-family: Raleway;
  padding: 10px;
  width: 90%;
  min-width: 300px;
}

h1 {
  text-align: center;
}

input {
  padding: 10px;
  width: 100%;
  font-size: 17px;
  font-family: Raleway;
  border: 1px solid #aaaaaa;
}

input.invalid {
  background-color: #ffdddd;
}

.tab {
  display: none;
}

button {
  background-color: #04AA6D;
  color: #ffffff;
  border: none;
  padding: 10px 20px;
  font-size: 17px;
  font-family: Raleway;
  cursor: pointer;
}

button:hover {
  opacity: 0.8;
}

#prevBtn {
  background-color: #bbbbbb;
}

.step {
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbbbbb;
  border: none;
  border-radius: 50%;
  display: inline-block;
  opacity: 0.5;
}

.step.active {
  opacity: 1;
}

.step.finish {
  background-color: #04AA6D;
}

.autocomplete {
  position: relative;
  display: inline-block;
}

.autocomplete-items {
  position: absolute;
  border: 1px solid #d4d4d4;
  border-bottom: none;
  border-top: none;
  z-index: 99;
  /*position the autocomplete items to be the same width as the container:*/
  top: 100%;
  left: 0;
  right: 0;
}

.autocomplete-items div {
  padding: 10px;
  cursor: pointer;
  background-color: #fff;
  border-bottom: 1px solid #d4d4d4;
}

.autocomplete-items div:hover {
  /*when hovering an item:*/
  background-color: #e9e9e9;
}

.autocomplete-active {
  /*when navigating through the items using the arrow keys:*/
  background-color: DodgerBlue !important;
  color: #fff;
}
</style>
</head>
<body>

<form id="regForm" action="/submit_page.php">
  <h1>Your Nutrition Needs:</h1>
  <div class="tab">Your Fruit:
    <p class="autocomplete">
      <input id="myFruitList" type="text" name="fruit" placeholder="Start typing your fruit name"></p>
  </div>
</form>

<script>
function autocomplete(inp, arr) {
  var currentFocus;
  var originalArray = [...arr];

  inp.addEventListener("input", function(e) {
    var a, b, i, val = this.value;
    closeAllLists();
    if (!val) {
        a = document.createElement("DIV");
        a.setAttribute("id", this.id + "autocomplete-list");
        a.setAttribute("class", "autocomplete-items");
        this.parentNode.appendChild(a);
        for (i = 0; i < arr.length; i++) {
            b = document.createElement("DIV");
            b.innerHTML = arr[i];
            b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
            b.addEventListener("click", function(e) {
                inp.value = this.getElementsByTagName("input")[0].value;
                closeAllLists();
            });
            a.appendChild(b);
        }
        return false;
    }
    currentFocus = -1;
    a = document.createElement("DIV");
    a.setAttribute("id", this.id + "autocomplete-list");
    a.setAttribute("class", "autocomplete-items");
    this.parentNode.appendChild(a);
    for (i = 0; i < arr.length; i++) {
      if (arr[i].toUpperCase().indexOf(val.toUpperCase()) > -1) {
        b = document.createElement("DIV");
        let index = arr[i].toUpperCase().indexOf(val.toUpperCase());
        let pre = arr[i].substring(0, index);
        let match = arr[i].substring(index, index + val.length);
        let post = arr[i].substring(index + val.length);
        b.innerHTML = pre + "<strong>" + match + "</strong>" + post;
        b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
        b.addEventListener("click", function(e) {
          inp.value = this.getElementsByTagName("input")[0].value;
          closeAllLists();
        });
        a.appendChild(b);
      }
    }
  });

  inp.addEventListener("keydown", function(e) {
    var x = document.getElementById(this.id + "autocomplete-list");
    if (x) x = x.getElementsByTagName("div");
    if (e.keyCode == 40) {
      currentFocus++;
      addActive(x);
    } else if (e.keyCode == 38) {
      currentFocus--;
      addActive(x);
    } else if (e.keyCode == 13) {
      e.preventDefault();
      if (currentFocus > -1) {
        if (x) x[currentFocus].click();
      }
    }
  });

  inp.addEventListener("blur", function(e) {
    if (originalArray.indexOf(inp.value) === -1 && inp.value !== "") {
        inp.value = "";
        alert("Please select a valid fruit from the list.");
    }
  });

  function addActive(x) {
    if (!x) return false;
    removeActive(x);
    if (currentFocus >= x.length) currentFocus = 0;
    if (currentFocus < 0) currentFocus = (x.length - 1);
    x[currentFocus].classList.add("autocomplete-active");
  }

  function removeActive(x) {
    for (var i = 0; i < x.length; i++) {
      x[i].classList.remove("autocomplete-active");
    }
  }

  function closeAllLists(elmnt) {
    var x = document.getElementsByClassName("autocomplete-items");
    for (var i = 0; i < x.length; i++) {
      if (elmnt != x[i] && elmnt != inp) {
        x[i].parentNode.removeChild(x[i]);
      }
    }
  }

  document.addEventListener("click", function(e) {
    closeAllLists(e.target);
  });
}

var fruitlist = [
  "Apple",
  "Mango",
  "Pear",
  "Banana",
  "Berry"
];

autocomplete(document.getElementById("myFruitList"), fruitlist);
</script>

</body>
</html>

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