在网上看了很多用js 将光标移动到textarea的最后，但是看了很多方法，不管用，浪费时间，最近用到一个新方法
=IE支持document.selection
=Firefox，Chrome,Safari以及Opera都有selectionStart和selectionEnd属性
function insertText(obj,str) {
obj.focus();
if (document.selection) {
var sel = document.selection.createRange();
sel.text = str;
} else if (typeof obj.selectionStart === 'number' && typeof obj.selectionEnd === 'number') {
var startPos = obj.selectionStart,
endPos = obj.selectionEnd,
cursorPos = startPos,
tmpStr = obj.value;
obj.value = tmpStr.substring(0, startPos) + str + tmpStr.substring(endPos, tmpStr.length);
cursorPos += str.length;
obj.selectionStart = obj.selectionEnd = cursorPos;
} else {
obj.value += str;
}
}
function moveEnd(obj){
obj.focus();
var len = obj.value.length;
if (document.selection) {
var sel = obj.createTextRange();
sel.moveStart('character',len);
sel.collapse();
sel.select();
} else if (typeof obj.selectionStart == 'number' && typeof obj.selectionEnd == 'number') {
obj.selectionStart = obj.selectionEnd = len;
}
if (document.selection) {
var sel = document.selection.createRange();
sel.text = str;
} else if (typeof obj.selectionStart === 'number' && typeof obj.selectionEnd === 'number') {
var startPos = obj.selectionStart,
endPos = obj.selectionEnd,
cursorPos = startPos,
tmpStr = obj.value;
obj.value = tmpStr.substring(0, startPos) + str + tmpStr.substring(endPos, tmpStr.length);
cursorPos += str.length;
obj.selectionStart = obj.selectionEnd = cursorPos;
} else {
obj.value += str;
}
}
function moveEnd(obj){
obj.focus();
var len = obj.value.length;
if (document.selection) {
var sel = obj.createTextRange();
sel.moveStart('character',len);
sel.collapse();
sel.select();
} else if (typeof obj.selectionStart == 'number' && typeof obj.selectionEnd == 'number') {
obj.selectionStart = obj.selectionEnd = len;
}
}