新浪的库操作textarea的工具函数

这篇文章主要为大家详细介绍了新浪的库操作textarea的工具函数示例，具有一定的参考价值，可以用来参考一下。

/**
 * 操作textarea的工具函数
 *
 * @param 
 * @arrange （www.idcnote.com）
 **/
App.TextareaUtils = (function () {
  var it = {},
    ds = document.selection;
  it.selectionStart = function (oElement) {
    if (!ds) {
      return oElement.selectionStart
    }
    var er = ds.createRange(),
      value, len, s = 0;
    var er1 = document.body.createTextRange();
    er1.moveToElementText(oElement);
    for (s; er1.compareEndPoints("StartToStart", er) < 0; s++) {
      er1.moveStart("character", 1)
    }
    return s
  };
  it.selectionBefore = function (oElement) {
    return oElement.value.slice(0, it.selectionStart(oElement))
  };
  it.selectText = function (oElement, nStart, nEnd) {
    oElement.focus();
    if (!ds) {
      oElement.setSelectionRange(nStart, nEnd);
      return
    }
    var c = oElement.createTextRange();
    c.collapse(1);
    c.moveStart("character", nStart);
    c.moveEnd("character", nEnd - nStart);
    c.select()
  };
  it.insertText = function (oElement, sInsertText, nStart, nLen) {
    oElement.focus();
    nLen = nLen || 0;
    if (!ds) {
      var text = oElement.value,
        start = nStart - nLen,
        end = start + sInsertText.length;
      oElement.value = text.slice(0, start) + sInsertText + text.slice(nStart, text.length);
      it.selectText(oElement, end, end);
      return
    }
    var c = ds.createRange();
    c.moveStart("character", -nLen);
    c.text = sInsertText
  };
  it.getCursorPos = function (obj) {
    var CaretPos = 0;
    if ($IE) {
      obj.focus();
      var range = null;
      range = ds.createRange();
      var stored_range = range.duplicate();
      stored_range.moveToElementText(obj);
      stored_range.setEndPoint("EndToEnd", range);
      obj.selectionStart = stored_range.text.length - range.text.length;
      obj.selectionEnd = obj.selectionStart + range.text.length;
      CaretPos = obj.selectionStart
    } else {
      if (obj.selectionStart || obj.selectionStart == "0") {
        CaretPos = obj.selectionStart
      }
    }
    return CaretPos
  };
  it.getSelectedText = function (obj) {
    var selectedText = "";
    var getSelection = function (e) {
      if (e.selectionStart != undefined && e.selectionEnd != undefined) {
        return e.value.substring(e.selectionStart, e.selectionEnd)
      } else {
        return ""
      }
    };
    if (window.getSelection) {
      selectedText = getSelection(obj)
    } else {
      selectedText = ds.createRange().text
    }
    return selectedText
  };
  it.setCursor = function (obj, pos, coverlen) {
    pos = pos == null ? obj.value.length : pos;
    coverlen = coverlen == null ? 0 : coverlen;
    obj.focus();
    if (obj.createTextRange) {
      var range = obj.createTextRange();
      range.move("character", pos);
      range.moveEnd("character", coverlen);
      range.select()
    } else {
      obj.setSelectionRange(pos, pos + coverlen)
    }
  };
  it.unCoverInsertText = function (obj, str, pars) {
    pars = (pars == null) ? {} : pars;
    pars.rcs = pars.rcs == null ? obj.value.length : pars.rcs * 1;
    pars.rccl = pars.rccl == null ? 0 : pars.rccl * 1;
    var text = obj.value,
      fstr = text.slice(0, pars.rcs),
      lstr = text.slice(pars.rcs + pars.rccl, text == "" ? 0 : text.length);
    obj.value = fstr + str + lstr;
    this.setCursor(obj, pars.rcs + (str == null ? 0 : str.length))
  };
  return it
})();

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