これは、この回答からiframeを操作するように適応されたクロスブラウザの例です。
function pasteHtmlAtCaret(html, selectPastedContent, iframe) {
var sel, range;
var win = iframe ? iframe.contentWindow : window;
var doc = win.document;
if (win.getSelection) {
// IE9 and non-IE
sel = win.getSelection();
if (sel.getRangeAt && sel.rangeCount) {
range = sel.getRangeAt(0);
range.deleteContents();
// Range.createContextualFragment() would be useful here but is
// only relatively recently standardized and is not supported in
// some browsers (IE9, for one)
var el = doc.createElement("div");
el.innerHTML = html;
var frag = doc.createDocumentFragment(), node, lastNode;
while ( (node = el.firstChild) ) {
lastNode = frag.appendChild(node);
}
var firstNode = frag.firstChild;
range.insertNode(frag);
// Preserve the selection
if (lastNode) {
range = range.cloneRange();
range.setStartAfter(lastNode);
if (selectPastedContent) {
range.setStartBefore(firstNode);
} else {
range.collapse(true);
}
sel.removeAllRanges();
sel.addRange(range);
}
}
} else if ( (sel = doc.selection) && sel.type != "Control") {
// IE < 9
var originalRange = sel.createRange();
originalRange.collapse(true);
sel.createRange().pasteHTML(html);
if (selectPastedContent) {
range = sel.createRange();
range.setEndPoint("StartToStart", originalRange);
range.select();
}
}
}