用户输入无法识别点击自动完成

Question

我正在尝试创建一个搜索框，根据用户输入显示选择选项，我正在使用 html 自动完成功能，当用户开始输入时，它提供来自 js var 的用户选项，问题是选择选项仅在以下情况下显示我在搜索框中输入“item1”（在这种情况下）并单击自动完成选项，如果我只输入例如“it”并在自动完成选项中单击“item1”，那么选择选项不会显示？？？ ？？？ https://jsfiddle.net/JohnONeil/Lcs4brxy/105/ 很确定它在这里

if ($(this).val() == 'item1')
  $("#userinput").change(function () {
    if ($(this).val() == 'item1') {
      $('#userinput1div').show();
      $('#userinput1').attr('required', '');
      $('userinput1').attr('data-error', 'This field is required.');
    }
    else {
      $('#userinput1div').hide();
      $('#userinput1').removeAttr('required');
      $('#userinput1').removeAttr('data-error');
    }
    if ($(this).val() == 'item2') {
      $('#userinput2div').show();
      $('#userinput2').attr('required', '');
      $('userinput2').attr('data-error', 'This field is required.');
    } else {
      $('#userinput2div').hide();
      $('#userinput2').removeAttr('required');
      $('#userinput2').removeAttr('data-error');

    }
  });
$("#userinput").trigger("change");  

演示：

function autocomplete(inp, arr) {
  /*the autocomplete function takes two arguments,
  the text field element and an array of possible autocompleted values:*/
  var currentFocus;
  /*execute a function when someone writes in the text field:*/
  inp.addEventListener("input", function(e) {
    var a, b, i, val = this.value;
    /*close any already open lists of autocompleted values*/
    closeAllLists();
    if (!val) {
      return false;
    }
    currentFocus = -1;
    /*create a DIV element that will contain the items (values):*/
    a = document.createElement("DIV");
    a.setAttribute("id", this.id + "autocomplete-list");
    a.setAttribute("class", "autocomplete-items");
    /*append the DIV element as a child of the autocomplete container:*/
    this.parentNode.appendChild(a);
    /*for each item in the array...*/
    for (i = 0; i < arr.length; i++) {
      /*check if the item starts with the same letters as the text field value:*/
      if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {
        /*create a DIV element for each matching element:*/
        b = document.createElement("DIV");
        /*make the matching letters bold:*/
        b.innerHTML = "<strong>" + arr[i].substr(0, val.length) + "</strong>";
        b.innerHTML += arr[i].substr(val.length);
        /*insert a input field that will hold the current array item's value:*/
        b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
        /*execute a function when someone clicks on the item value (DIV element):*/
        b.addEventListener("click", function(e) {
          /*insert the value for the autocomplete text field:*/
          inp.value = this.getElementsByTagName("input")[0].value;
          /*close the list of autocompleted values,
          (or any other open lists of autocompleted values:*/
          closeAllLists();
        });
        a.appendChild(b);
      }
    }
  });
  /*execute a function presses a key on the keyboard:*/
  inp.addEventListener("keydown", function(e) {
    var x = document.getElementById(this.id + "autocomplete-list");
    if (x) x = x.getElementsByTagName("div");
    if (e.keyCode == 40) {
      /*If the arrow DOWN key is pressed,
      increase the currentFocus variable:*/
      currentFocus++;
      /*and and make the current item more visible:*/
      addActive(x);
    } else if (e.keyCode == 38) { //up
      /*If the arrow UP key is pressed,
      decrease the currentFocus variable:*/
      currentFocus--;
      /*and and make the current item more visible:*/
      addActive(x);
    } else if (e.keyCode == 13) {
      /*If the ENTER key is pressed, prevent the form from being submitted,*/
      e.preventDefault();
      if (currentFocus > -1) {
        /*and simulate a click on the "active" item:*/
        if (x) x[currentFocus].click();
      }
    }
  });

  function addActive(x) {
    /*a function to classify an item as "active":*/
    if (!x) return false;
    /*start by removing the "active" class on all items:*/
    removeActive(x);
    if (currentFocus >= x.length) currentFocus = 0;
    if (currentFocus < 0) currentFocus = (x.length - 1);
    /*add class "autocomplete-active":*/
    x[currentFocus].classList.add("autocomplete-active");
  }

  function removeActive(x) {
    /*a function to remove the "active" class from all autocomplete items:*/
    for (var i = 0; i < x.length; i++) {
      x[i].classList.remove("autocomplete-active");
    }
  }

  function closeAllLists(elmnt) {
    /*close all autocomplete lists in the document,
    except the one passed as an argument:*/
    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]);
      }
    }
  }
  /*execute a function when someone clicks in the document:*/
  document.addEventListener("click", function(e) {
    closeAllLists(e.target);
  });
}

$("#userinput").change(function() {
  if ($(this).val() == 'item1') {
    $('#userinput1div').show();
    $('#userinput1').attr('required', '');
    $('userinput1').attr('data-error', 'This field is required.');
  } else {
    $('#userinput1div').hide();
    $('#userinput1').removeAttr('required');
    $('#userinput1').removeAttr('data-error');
  }
  if ($(this).val() == 'item2') {
    $('#userinput2div').show();
    $('#userinput2').attr('required', '');
    $('userinput2').attr('data-error', 'This field is required.');
  } else {
    $('#userinput2div').hide();
    $('#userinput2').removeAttr('required');
    $('#userinput2').removeAttr('data-error');

  }
});

$("#userinput").trigger("change");
var items = ["item1", "item2", "item3"];
autocomplete(document.getElementById("userinput"), items);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>
<form autocomplete="off" action="">
  <div>
    <input type="text" id="userinput" placeholder="choose item">
  </div>
  <div id="userinput1div">
    <select id="userinput1">
      <option hidden>Choose sub item</option>
      <option>item1a</option>
      <option>item1b</option>
    </select>
  </div>
  <div id="userinput2div">
    <select id="userinput2">
      <option hidden>Choose sub item</option>
      <option>item2a</option>
      <option>item2b</option>
    </select>
  </div>
  <button type="submit" class="btn btn-primary">Submit</button>
</form>

Answer 1

编辑：您反对为此使用jQuery Autocomplete 之类的东西吗？我继续创建了一个演示，如果你使用它会是什么样子。它使事情变得超级简单。请参阅下面标题为 DEMO WITH jQuery- 的 sn-p用户界面。

原始答案： 这是因为您在 autocomplete 函数中设置值的方式。处理程序方法读取之前输入的值autocomplete 函数可以设置输入的值。

我建议微调您的 autocomplete 函数，或更改设置值背后的逻辑。

原始演示

function autocomplete(inp, arr) {
  /*the autocomplete function takes two arguments,
  the text field element and an array of possible autocompleted values:*/
  var currentFocus;
  /*execute a function when someone writes in the text field:*/
  inp.addEventListener("input", function(e) {
    var a, b, i, val = this.value;
    /*close any already open lists of autocompleted values*/
    closeAllLists();
    if (!val) {
      return false;
    }
    currentFocus = -1;
    /*create a DIV element that will contain the items (values):*/
    a = document.createElement("DIV");
    a.setAttribute("id", this.id + "autocomplete-list");
    a.setAttribute("class", "autocomplete-items");
    /*append the DIV element as a child of the autocomplete container:*/
    this.parentNode.appendChild(a);
    /*for each item in the array...*/
    for (i = 0; i < arr.length; i++) {
      /*check if the item starts with the same letters as the text field value:*/
      if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {
        /*create a DIV element for each matching element:*/
        b = document.createElement("DIV");
        /*make the matching letters bold:*/
        b.innerHTML = "<strong>" + arr[i].substr(0, val.length) + "</strong>";
        b.innerHTML += arr[i].substr(val.length);
        /*insert a input field that will hold the current array item's value:*/
        b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
        /*execute a function when someone clicks on the item value (DIV element):*/
        b.addEventListener("click", function(e) {
          /*insert the value for the autocomplete text field:*/
          inp.value = this.getElementsByTagName("input")[0].value;
          alert("CURRENT VAL: ' " +inp.value + " '\r\n\r\n^^^ Then the clicked value is set, via 'autocomplete' function [specifically the 'b.addEventListener('click',..)' handler is where you set the value]\r\n\r\n--This is only working right now because I wrapped the '$('#userinput').change' handler function in a setTimeout! (which you SHOULD NOT DO to fix this!!!)\r\n\r\n");
          /*close the list of autocompleted values,
          (or any other open lists of autocompleted values:*/
          closeAllLists();
        });
        a.appendChild(b);
      }
    }
  });
  /*execute a function presses a key on the keyboard:*/
  inp.addEventListener("keydown", function(e) {
    var x = document.getElementById(this.id + "autocomplete-list");
    if (x) x = x.getElementsByTagName("div");
    if (e.keyCode == 40) {
      /*If the arrow DOWN key is pressed,
      increase the currentFocus variable:*/
      currentFocus++;
      /*and and make the current item more visible:*/
      addActive(x);
    } else if (e.keyCode == 38) { //up
      /*If the arrow UP key is pressed,
      decrease the currentFocus variable:*/
      currentFocus--;
      /*and and make the current item more visible:*/
      addActive(x);
    } else if (e.keyCode == 13) {
      /*If the ENTER key is pressed, prevent the form from being submitted,*/
      e.preventDefault();
      if (currentFocus > -1) {
        /*and simulate a click on the "active" item:*/
        if (x) x[currentFocus].click();
      }
    }
  });

  function addActive(x) {
    /*a function to classify an item as "active":*/
    if (!x) return false;
    /*start by removing the "active" class on all items:*/
    removeActive(x);
    if (currentFocus >= x.length) currentFocus = 0;
    if (currentFocus < 0) currentFocus = (x.length - 1);
    /*add class "autocomplete-active":*/
    x[currentFocus].classList.add("autocomplete-active");
  }

  function removeActive(x) {
    /*a function to remove the "active" class from all autocomplete items:*/
    for (var i = 0; i < x.length; i++) {
      x[i].classList.remove("autocomplete-active");
    }
  }

  function closeAllLists(elmnt) {
    /*close all autocomplete lists in the document,
    except the one passed as an argument:*/
    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]);
      }
    }
  }
  /*execute a function when someone clicks in the document:*/
  document.addEventListener("click", function(e) {
    closeAllLists(e.target);
  });
}

$("#userinput").change(function() {
  if ($(this).val()) {
    alert("CURRENT VAL: ' " + $(this).val() + " '\r\n\r\n^^^ At this stage, in the $('#userinput').change(..) handler, whatever was typed is the current .val() - this is why it is not working..\r\n\r\n");
  }
  setTimeout(() => {
    if ($(this).val() == 'item1') {
      $('#userinput1div').show();
      $('#userinput1').attr('required', '');
      $('userinput1').attr('data-error', 'This field is required.');
    } else {
      $('#userinput1div').hide();
      $('#userinput1').removeAttr('required');
      $('#userinput1').removeAttr('data-error');
    }
    if ($(this).val() == 'item2') {
      $('#userinput2div').show();
      $('#userinput2').attr('required', '');
      $('userinput2').attr('data-error', 'This field is required.');
    } else {
      $('#userinput2div').hide();
      $('#userinput2').removeAttr('required');
      $('#userinput2').removeAttr('data-error');
    }
  }, 300);
});

$("#userinput").trigger("change");
var items = ["item1", "item2", "item3"];
autocomplete(document.getElementById("userinput"), items);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="stylesheet" />
<link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" />
<p style="margin-bottom:0px"><small>Type "it" then click on 'item1'</small></p>
<form autocomplete="off" action="">
  <div>
    <input type="text" id="userinput" placeholder="choose item">
  </div>
  <div id="userinput1div">
    <select id="userinput1">
      <option hidden>Choose sub item</option>
      <option>item1a</option>
      <option>item1b</option>
    </select>
  </div>
  <div id="userinput2div">
    <select id="userinput2">
      <option hidden>Choose sub item</option>
      <option>item2a</option>
      <option>item2b</option>
    </select>
  </div>
  <button type="submit" class="btn btn-primary">Submit</button>
</form>

使用 jQuery-UI 演示

$("#userinput1div").hide();
$("#userinput2div").hide();

const choices = ["item1", "item2", "item3"];

$("#userinput").autocomplete({
  source: choices,
  select: function(event, ui) {
    handleChange(ui.item.value);
  }
});

function handleChange(val) {
  if (val == "item1") {
    $("#userinput1div").show();
    $("#userinput1").attr("required", "");
    $("userinput1").attr("data-error", "This field is required.");
  } else {
    $("#userinput1div").hide();
    $("#userinput1").removeAttr("required");
    $("#userinput1").removeAttr("data-error");
  }
  if (val == "item2") {
    $("#userinput2div").show();
    $("#userinput2").attr("required", "");
    $("userinput2").attr("data-error", "This field is required.");
  } else {
    $("#userinput2div").hide();
    $("#userinput2").removeAttr("required");
    $("#userinput2").removeAttr("data-error");
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>
<link href="https://code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css" rel="stylesheet"/>
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>

<form autocomplete="off" action="">
  <div>
    <input type="text" id="userinput" placeholder="choose item">
  </div>
  <div id="userinput1div">
    <select id="userinput1">
      <option hidden>Choose sub item</option>
      <option>item1a</option>
      <option>item1b</option>
    </select>
  </div>
  <div id="userinput2div">
    <select id="userinput2">
      <option hidden>Choose sub item</option>
      <option>item2a</option>
      <option>item2b</option>
    </select>
  </div>
  <button type="submit" class="btn btn-primary">Submit</button>
</form>