javascript - Document .focus() 在网页加载时有效，但在刷新时无效
问题描述
我有一个 HTML 表单，我使用它<body onload="setFocusToInput();">来确保输入字段具有焦点。
但这仅适用于新页面，如果刷新网页，我会失去所有焦点。
是否有一些相当于检测刷新以便我可以重置焦点？
已更新，这是重现错误的页面的小而草率的副本
<!DOCTYPE html>
<html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<style type="text/css">
body
{
padding-top: 100px;
}
* { box-sizing: border-box; }
body {
font: 16px Arial;
}
.autocomplete {
position: relative;
display: inline-block;
}
input
{
border: 1px solid ;
padding: 5px;
font-size: 24px;
}
input[type=text]
{
border-color: #808080;
background-color: #fff;
width: 100%;
-webkit-border-radius: 5px;
padding:5px;
}
input[type=submit]
{
margin-left: 5px;
padding:5px;
background:#ccc;
cursor:pointer;
-webkit-border-radius: 5px;
border: 1px solid ;
background-color: DodgerBlue;
border-color: #CCCCCC;
color : #fff;
}
.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: #ffffff;
/*when hovering an item:*/
<script type="text/javascript">
}
</style>
</head>
<body onload="setFocusToInput();">
<table >
<tr>
<td>
<!-- <input id="myBanner" type="text" name=" " placeholder=""> -->
</td>
<td>
</td>
</tr>
<tr>
<td>
<!--Make sure the form has the autocomplete function switched off:-->
<form autocomplete="off" action="/cgi-bin/prl.pl">
<div class="autocomplete" style="width:300px;">
<input id="myInput" type="text" name="myCountry" placeholder="Pick a country..." autofocus>
</div>
</td>
<td style="width:150px;">
<input id="113" type="submit" value="Go">
</form>
</td>
</tr>
</table>
<script>
function setFocusToInput(){
var textbox = document.getElementById("myInput");
//var y = document.getElementById("myBanner");
//y.value = textbox;
textbox.focus();
}
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...*/
/////////////////////////////////////////////////////////
var x = 0;
var regex = new RegExp(val, 'i');
arr.filter(str => str.match(regex))
.forEach(str =>
{
x = x + 1;
var y = val.length;
var lowerstr = str.toLowerCase();
var lowerval = val.toLowerCase();
var n = lowerstr.indexOf(lowerval);
var z = str.length;
b = document.createElement("DIV");
/*make the matching letters bold:*/
if(n == 0)
{
b.innerHTML = "<strong>" + str.substr(0, val.length) + "</strong>";
b.innerHTML += str.substr(y);
}
else
{
b.innerHTML = str.substr(0, n);
b.innerHTML += "<strong>" + str.substr(n, y) + "</strong>";
b.innerHTML += str.substr(n+y);
}
// b.innerHTML = str;
/*insert a input field that will hold the current array item's value:*/
b.innerHTML += "<input type='hidden' value='" + str + "'>";
/*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");
//var y = document.getElementById("myReader");
//y.value = x;
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();
document.getElementById("113").focus();
}
}
}
});
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);
});
}
/*An array containing all the country names in the world:*/
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"];
/*initiate the autocomplete function on the "myInput" element, and pass along the countries array as possible autocomplete values:*/
autocomplete(document.getElementById("myInput"), countries);
</script>
</body>
</html>
解决方案
一旦网页完全加载了所有内容，onload 最常在元素中使用以执行脚本。但是 - 它也可以用于其他元素。
对于输入元素，您可以尝试使用本机属性autofocus- 一个布尔值，如果存在，则在呈现表单时使输入成为焦点。
认为autofocus有一些限制；文档中不超过一个元素可能具有该autofocus属性，并且autofocus不能用于隐藏类型的输入，因为隐藏的输入无法聚焦。
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