如何用原生JavaScript实现文本中间匹配的Autocomplete功能

针对W3Schools的自动补全组件，要实现文本中间匹配（如输入"exi"匹配Mexico），只需修改两处核心逻辑，以下是完整的原生JS解决方案：

修改后的完整代码 #

HTML #

<!-- 关闭表单默认自动补全 -->
<form autocomplete="off" action="/action_page.php">
  <div class="autocomplete" style="width:300px;">
    <input id="myInput" type="text" name="myCountry" placeholder="Country">
  </div>
  <input type="submit">
</form>

JavaScript #

function autocomplete(inp, arr) {
  var currentFocus;

  inp.addEventListener("input", function(e) {
    var a, b, i, val = this.value;
    closeAllLists();
    if (!val) 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++) {
      // 核心修改1：判断字符串是否包含输入值（不区分大小写）
      const valUpper = val.toUpperCase();
      const itemUpper = arr[i].toUpperCase();
      if (itemUpper.includes(valUpper)) {
        b = document.createElement("DIV");
        // 核心修改2：高亮所有匹配的子串（支持中间位置）
        const matchIndex = itemUpper.indexOf(valUpper);
        // 拼接高亮后的内容
        b.innerHTML = arr[i].substr(0, matchIndex) + 
                      "<strong>" + arr[i].substr(matchIndex, val.length) + "</strong>" + 
                      arr[i].substr(matchIndex + 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);
      }
    }
  });

  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();
      }
    }
  });

  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);
  });
}

// 国家列表数组
var countries = ["Afghanistan", "Albania", "Algeria", "Andorra", "Angola", "Anguilla", "Antigua & Barbuda", "Argentina", "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan", "Bahamas", "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium", "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia", "Bosnia & Herzegovina", "Botswana", "Brazil", "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burundi", "Cambodia", "Cameroon", "Canada", "Cape Verde", "Cayman Islands", "Central Arfrican Republic", "Chad", "Chile", "China", "Colombia", "Congo", "Cook Islands", "Costa Rica", "Cote D Ivoire", "Croatia", "Cuba", "Curacao", "Cyprus", "Czech Republic", "Denmark", "Djibouti", "Dominica", "Dominican Republic", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea", "Estonia", "Ethiopia", "Falkland Islands", "Faroe Islands", "Fiji", "Finland", "France", "French Polynesia", "French West Indies", "Gabon", "Gambia", "Georgia", "Germany", "Ghana", "Gibraltar", "Greece", "Greenland", "Grenada", "Guam", "Guatemala", "Guernsey", "Guinea", "Guinea Bissau", "Guyana", "Haiti", "Honduras", "Hong Kong", "Hungary", "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Isle of Man", "Israel", "Italy", "Jamaica", "Japan", "Jersey", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kosovo", "Kuwait", "Kyrgyzstan", "Laos", "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg", "Macau", "Macedonia", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Marshall Islands", "Mauritania", "Mauritius", "Mexico", "Micronesia", "Moldova", "Monaco", "Mongolia", "Montenegro", "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia", "Nauro", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand", "Nicaragua", "Niger", "Nigeria", "North Korea", "Norway", "Oman", "Pakistan", "Palau", "Palestine", "Panama", "Papua New Guinea", "Paraguay", "Peru", "Philippines", "Poland", "Portugal", "Puerto Rico", "Qatar", "Reunion", "Romania", "Russia", "Rwanda", "Saint Pierre & Miquelon", "Samoa", "San Marino", "Sao Tome and Principe", "Saudi Arabia", "Senegal", "Serbia", "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands", "Somalia", "South Africa", "South Korea", "South Sudan", "Spain", "Sri Lanka", "St Kitts & Nevis", "St Lucia", "St Vincent", "Sudan", "Suriname", "Swaziland", "Sweden", "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "Timor L'Este", "Togo", "Tonga", "Trinidad & Tobago", "Tunisia", "Turkey", "Turkmenistan", "Turks & Caicos", "Tuvalu", "Uganda", "Ukraine", "United Arab Emirates", "United Kingdom", "United States of America", "Uruguay", "Uzbekistan", "Vanuatu", "Vatican City", "Venezuela", "Vietnam", "Virgin Islands (US)", "Yemen", "Zambia", "Zimbabwe"];

// 初始化自动补全
autocomplete(document.getElementById("myInput"), countries);

关键修改说明 #

1. 匹配逻辑调整：将原有的开头匹配判断替换为itemUpper.includes(valUpper)，实现任意位置的子串匹配，且不区分大小写。
2. 高亮逻辑优化：通过itemUpper.indexOf(valUpper)找到匹配子串的起始位置，拆分字符串并拼接高亮部分，确保中间匹配的内容也能正确高亮。

内容的提问来源于stack exchange，提问作者Oříšek