如何在textarea中处理<tab>？

Question

我想要一个处理按Tab键情况的textarea .

在默认情况下,如果按Tab键,则焦点将离开textarea.但是当用户想要在textarea中键入tab键时呢？

我可以捕获此事件并将焦点返回到textarea并将标签添加到当前光标位置吗？

Answer 1

你可以:http://jsfiddle.net/sdDVf/8/.

$("textarea").keydown(function(e) {
    if(e.keyCode === 9) { // tab was pressed
        // get caret position/selection
        var start = this.selectionStart;
        var end = this.selectionEnd;

        var $this = $(this);
        var value = $this.val();

        // set textarea value to: text before caret + tab + text after caret
        $this.val(value.substring(0, start)
                    + "\t"
                    + value.substring(end));

        // put caret at right position again (add one for the tab)
        this.selectionStart = this.selectionEnd = start + 1;

        // prevent the focus lose
        e.preventDefault();
    }
});

Answer 2

这是pimvdb答案的修改版本,不需要JQuery:

document.querySelector("textarea").addEventListener('keydown',function(e) {
    if(e.keyCode === 9) { // tab was pressed
        // get caret position/selection
        var start = this.selectionStart;
        var end = this.selectionEnd;

        var target = e.target;
        var value = target.value;

        // set textarea value to: text before caret + tab + text after caret
        target.value = value.substring(0, start)
                    + "\t"
                    + value.substring(end);

        // put caret at right position again (add one for the tab)
        this.selectionStart = this.selectionEnd = start + 1;

        // prevent the focus lose
        e.preventDefault();
    }
},false);

我在Firefox 21.0和Chrome 27中进行了测试.不知道它是否适用于其他任何地方.

Answer 3

好上帝,所有以前的答案都未能提供通常不错的(即程序员)标签控件.

也就是说,TAB选择行的命中将缩进这些行,SHIFTTAB并将取消缩进它们.

_edited(2016年11月):keyCode替换为charCode || keyCode,每个KeyboardEvent.charCode - Web API | MDN

(function($) {
  $.fn.enableSmartTab = function() {
    var $this;
    $this = $(this);
    $this.keydown(function(e) {
      var after, before, end, lastNewLine, changeLength, re, replace, selection, start, val;
      if ((e.charCode === 9 || e.keyCode === 9) && !e.altKey && !e.ctrlKey && !e.metaKey) {
        e.preventDefault();
        start = this.selectionStart;
        end = this.selectionEnd;
        val = $this.val();
        before = val.substring(0, start);
        after = val.substring(end);
        replace = true;
        if (start !== end) {
          selection = val.substring(start, end);
          if (~selection.indexOf('\n')) {
            replace = false;
            changeLength = 0;
            lastNewLine = before.lastIndexOf('\n');
            if (!~lastNewLine) {
              selection = before + selection;
              changeLength = before.length;
              before = '';
            } else {
              selection = before.substring(lastNewLine) + selection;
              changeLength = before.length - lastNewLine;
              before = before.substring(0, lastNewLine);
            }
            if (e.shiftKey) {
              re = /(\n|^)(\t|[ ]{1,8})/g;
              if (selection.match(re)) {
                start--;
                changeLength--;
              }
              selection = selection.replace(re, '$1');
            } else {
              selection = selection.replace(/(\n|^)/g, '$1\t');
              start++;
              changeLength++;
            }
            $this.val(before + selection + after);
            this.selectionStart = start;
            this.selectionEnd = start + selection.length - changeLength;
          }
        }
        if (replace && !e.shiftKey) {
          $this.val(before + '\t' + after);
          this.selectionStart = this.selectionEnd = start + 1;
        }
      }
    });
  };
})(jQuery);

$(function() {
  $("textarea").enableSmartTab();
})

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea rows="10" cols="80">
/* Just some code to edit with our new superTab */
(function($) {
    $.fn.enableSmartTab = function() {
        $this = $(this);
        $this.keydown(function(e) {
            if ((e.charCode === 9 || e.keyCode === 9) && !e.metaKey && !e.ctrlKey && !e.altKey) {
                e.preventDefault();
            }
        }
    }
}
</textarea>

Answer 4

在Vanilla(默认)JS中,这将是:

  var textareas = document.getElementsByTagName('textarea');

  if ( textareas ) {
    for ( var i = 0; i < textareas.length; i++ ) {
      textareas[i].addEventListener( 'keydown', function ( e ) {
      if ( e.which != 9 ) return;

      var start 			= this.selectionStart;
      var end				  = this.selectionEnd;

      this.value 			= this.value.substr( 0, start ) + "\t" + this.value.substr( end );
      this.selectionStart = this.selectionEnd = start + 1;

      e.preventDefault();
      return false;
      });
    }
  }

textarea {
   border: 1px solid #cfcfcf;
   width: 100%;
   margin-left: 0px;
   top: 0px;
   bottom: 0px;
   position: absolute;
}

<textarea>

	var x = 10;
	var y = 10;

</textarea>