jQuery Set Cursor to Beginning of Input Field on Focus

问题

I have an input field <input value="@website.com" type="text" name="email" id="email"> and I want to make it so when a user focuses on this field, it will move the cursor to be before the @website.com.

I have the following Javascript/jQuery code but it does not seem to work:

$(document).ready(function() {
    $("#email").focusin(function(){
        $("#email").focus();
        $("#email")[0].setSelectionRange(0,0);
    });
});

It seems like the .focus() keeps calling the focusin() function.

I know $("#email")[0].setSelectionRange(0,0); is the proper way to move the cursor to the front but how do I bind it to when the field has focus?

Edit: So when I use:

$("#email").focus(function(){
    $("#email")[0].setSelectionRange(0,0);
});

It sets the cursor to the beginning when I tab into the field but not when I click in.

Edit2: This is different than enter link description here because that just gets the caret position whereas I am looking to set the caret position.

回答1:

This will bind the focus AND click events of the input field to the function. Hope this helps!

$('#email').on('focus click', function() {
  $(this)[0].setSelectionRange(0, 0);
})

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" placeholder="Enter your name" autofocus>
<input type="text" id="email" value="@website.com">

Or, without jQuery...

document.getElementById('email').addEventListener('click', moveCursor);
document.getElementById('email').addEventListener('focus', moveCursor);

function moveCursor(event) {
   event.target.setSelectionRange(0, 0);
}

<input type="text" placeholder="Enter your name" autofocus>
<input type="text" id="email" value="@website.com">

回答2:

Do you really need jQuery for this?

document.getElementById("email").addEventListener("click", moveCursor);
document.getElementById("email").addEventListener("focus", moveCursor);

function moveCursor(event) {
    event.target.setSelectionRange(0,0);
}

<input value="@website.com" type="text" name="email" id="email"></input>

回答3:

Whatever you want to perform with a cursor needs a field focus anyway.

Here is an old chunk I use. I even named it cursor.js in a sub-directory... I took it from many places I guess.

It's a get/set cursor position. It takes a JS element. .oO($(el)[0] for syntax loose..)

var isOpera = !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;
    // Opera 8.0+ (UA detection to detect Blink/v8-powered Opera)
var isFirefox = typeof InstallTrigger !== 'undefined';   // Firefox 1.0+
var isSafari = Object.prototype.toString.call(window.HTMLElement).indexOf('Constructor') > 0;
    // At least Safari 3+: "[object HTMLElementConstructor]"
var isChrome = !!window.chrome && !isOpera;              // Chrome 1+
var isIE = /*@cc_on!@*/false || !!document.documentMode; // At least IE6


function GetCursorPos (field) {

  // Initialize
  iCaretPos = 0;

  if (isIE){

    // Set focus on the element
    field.focus();

    // To get cursor position, get empty selection range
    oSel = field.createTextRange();

    // Move selection start to 0 position
    oSel.moveStart('character', -field.value.length);

    // The caret position is selection length
    iCaretPos = oSel.text.length;
  }

  if (isChrome||isSafari){
    iCaretPos = field.selectionStart;
  }

  if (isFirefox){
    iCaretPos = field.selectionStart;
  }

  return iCaretPos;
}

function SetCursorPos (field,Pos) {

  // Set focus on the element
    field.focus();

  if (isIE){
    field.selectionStart=Pos;
  }

  if (isChrome||isSafari){
    field.setSelectionRange(Pos,Pos);
  }

  if (isFirefox){
    field.selectionStart=Pos;
  }

  return;
}

About browser-friendly considerations, there is:

.selectionStart -- Chrome/Safari/Firefox
.setSelectionRange(Pos,Pos) -- Chrome/Safari/Firefox/Internet Explorer
.createTextRange() -- Internet Explorer

An inspiration I used upthere long ago: partial (compared to the above) SO answer

来源：https://stackoverflow.com/questions/51294827/jquery-set-cursor-to-beginning-of-input-field-on-focus

标签

javascript

jquery

focus