javascript - 将文本区域中的少量文本更改为粗体

Question

假设我有这段文字

Lorem ipsum dolor sit amet, consectetur adipiscing elit.

我要大胆

Lorem ipsum dolor sit amet, consectetur adipiscing elit.

如果我要在 Javascript 中执行此操作

function myFunction(obj) {
  var text1 = "Lorem ipsum ";
  var text2 = "dolor sit amet";
  var text3 = ", consectetur adipiscing elit.";
  text2.bold();
  
  obj.value = text1 + text2 + text3;
}

<textArea onmouseup=myFunction(this)>Lorem ipsum dolor sit amet, consectetur adipiscing elit</textArea>

我似乎无法将文本加粗，有什么想法吗？

Answer 1

因为您不能在 textarea 中设置文本样式，
下面是一个使用内容可编辑的 div 的解决方案:
(灵感来 self 对另一个问题的解决方案:Change font for selected text using JavaScript)

function changeStyle(style) {
  var sel = window.getSelection(); // Gets selection
  if (sel.rangeCount) {
    // Creates a new element, and insert the selected text with the chosen style
    var e = document.createElement('span');
    e.classList.add(style.value); // Selected style (class)
    e.innerHTML = sel.toString(); // Selected text

    // https://developer.mozilla.org/en-US/docs/Web/API/Selection/getRangeAt
    var range = sel.getRangeAt(0);
    range.deleteContents(); // Deletes selected text…
    range.insertNode(e); // … and inserts the new element at its place
  }
}

.editable {
  width: 360px;
  height: 120px;
  border: 1px solid #ccc
}

.editable .span-0{ /* Added to reset styles correctly */
  font-weight: normal;   /* Reset b */
  text-decoration: none; /* Reset u */
  font-style: normal;    /* Reset i */
}

.editable .span-b{
  font-weight: bold;
}

.editable .span-u{
  text-decoration: underline;
}

.editable .span-i{
  font-style: italic;
}

Highlight text and change style<br>
<select id="select_font" onchange="changeStyle(this);">
  <option value="span-0" selected>None</option>
  <option value="span-b">Bold</option>
  <option value="span-u">Underlined</option>
  <option value="span-i">Italic</option>
</select>
<div contenteditable="true" class="editable">
  Some Content
</div>

(我添加了其他样式选项……只是因为!)

希望对您有所帮助!