文本框中的字符串截取方法

function getSelectedText(textbox) {
if (document.selection) {
return document.selection.createRange().text;
} else {
return textbox.value.substring(textbox.selectionStart,textbox.selectionEnd);
}
}

function selectText(textbox, startIndex, stopIndex) {
if (textbox.setSelectionRange) {
textbox.setSelectionRange(startIndex, stopIndex);
} else if (textbox.createTextRange) {
var range = textbox.createTextRange();
range.collapse(true);
range.moveStart("character", startIndex);
range.moveEnd("character", stopIndex - startIndex);
range.select();
}
textbox.focus();
}