jQuery在文本区域中设置光标位置 [英] jQuery Set Cursor Position in Text Area

问题描述

如何使用 jQuery 在文本字段中设置光标位置?我有一个包含内容的文本字段，我希望用户光标在他们关注该字段时定位在某个偏移量处.代码应该是这样的:

How do you set the cursor position in a text field using jQuery? I've got a text field with content, and I want the users cursor to be positioned at a certain offset when they focus on the field. The code should look kind of like this:

$('#input').focus(function() {
  $(this).setCursorPosition(4);
});

setCursorPosition 函数的实现是什么样的?如果您有一个内容为 abcdefg 的文本字段，则此调用将导致光标定位如下:abcd**|**efg.

What would the implementation of that setCursorPosition function look like? If you had a text field with the content abcdefg, this call would result in the cursor being positioned as follows: abcd**|**efg.

Java 有一个类似的函数，setCaretPosition.javascript是否存在类似的方法?

Java has a similar function, setCaretPosition. Does a similar method exist for javascript?

更新:我修改了 CMS 的代码以使用 jQuery，如下所示:

new function($) {
  $.fn.setCursorPosition = function(pos) {
    if (this.setSelectionRange) {
      this.setSelectionRange(pos, pos);
    } else if (this.createTextRange) {
      var range = this.createTextRange();
      range.collapse(true);
      if(pos < 0) {
        pos = $(this).val().length + pos;
      }
      range.moveEnd('character', pos);
      range.moveStart('character', pos);
      range.select();
    }
  }
}(jQuery);

推荐答案

我有两个功能:

function setSelectionRange(input, selectionStart, selectionEnd) {
  if (input.setSelectionRange) {
    input.focus();
    input.setSelectionRange(selectionStart, selectionEnd);
  }
  else if (input.createTextRange) {
    var range = input.createTextRange();
    range.collapse(true);
    range.moveEnd('character', selectionEnd);
    range.moveStart('character', selectionStart);
    range.select();
  }
}

function setCaretToPos (input, pos) {
  setSelectionRange(input, pos, pos);
}

然后你可以像这样使用 setCaretToPos:

Then you can use setCaretToPos like this:

setCaretToPos(document.getElementById("YOURINPUT"), 4);

带有 textarea 和 input 的实时示例，展示了 jQuery 的使用:

Live example with both a textarea and an input, showing use from jQuery:

function setSelectionRange(input, selectionStart, selectionEnd) {
  if (input.setSelectionRange) {
    input.focus();
    input.setSelectionRange(selectionStart, selectionEnd);
  } else if (input.createTextRange) {
    var range = input.createTextRange();
    range.collapse(true);
    range.moveEnd('character', selectionEnd);
    range.moveStart('character', selectionStart);
    range.select();
  }
}

function setCaretToPos(input, pos) {
  setSelectionRange(input, pos, pos);
}

$("#set-textarea").click(function() {
  setCaretToPos($("#the-textarea")[0], 10)
});
$("#set-input").click(function() {
  setCaretToPos($("#the-input")[0], 10);
});

<textarea id="the-textarea" cols="40" rows="4">Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</textarea>
<br><input type="button" id="set-textarea" value="Set in textarea">
<br><input id="the-input" type="text" size="40" value="Lorem ipsum dolor sit amet, consectetur adipiscing elit">
<br><input type="button" id="set-input" value="Set in input">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

截至 2016 年，已在 Chrome、Firefox、IE11 甚至 IE8 上进行了测试和工作(请参阅最后一个此处；堆栈片段不支持 IE8).

As of 2016, tested and working on Chrome, Firefox, IE11, even IE8 (see that last here; Stack Snippets don't support IE8).

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