Collection of textarea operation methods encapsulated by js (very compatible)_javascript skills

var TT = {
/*
* Get cursor position
* @Method getCursorPosition
* @param t element
* @return number
*/
getCursorPosition: function(t){
if (document.selection) {
t.focus();
var ds = document.selection;
var range = ds.createRange();
var stored_range = range.duplicate();
stored_range.moveToElementText (t);
stored_range.setEndPoint("EndToEnd", range);
t.selectionStart = stored_range.text.length - range.text.length;
t.selectionEnd = t.selectionStart range.text .length;
return t.selectionStart;
} else return t.selectionStart
},
/*
* Set cursor position
* @Method setCursorPosition
* @param t element
* @param p number
* @return
*/
setCursorPosition:function(t, p){
this.sel(t,p,p);
},
/*
* Insert after the cursor
* @Method add
* @param t element
* @param txt String
* @return
*/
add:function (t, txt){
var val = t.value;
if(document.selection){
t.focus()
document.selection.createRange(). text = txt;
} else {
var cp = t.selectionStart;
var ubbLength = t.value.length;
var s = t.scrollTop;
// document.getElementById ('aaa').innerHTML = s '
';
t.value = t.value.slice(0,t.selectionStart) txt t.value.slice(t.selectionStart, ubbLength) ;
this.setCursorPosition(t, cp txt.length);
// document.getElementById('aaa').innerHTML = t.scrollTop '
';
firefox=navigator .userAgent.toLowerCase().match(/firefox/([d.] )/) && setTimeout(function(){
if(t.scrollTop != s) t.scrollTop=s;
}, 0)
};
},
/*
* Delete n characters before or after the cursor
* @Method del
* @param t element
* @ param n number n>0 followed by n<0 preceded by
* @return
* When resetting the value, the value of scrollTop will be cleared to 0
*/
del:function(t, n){
var p = this.getCursorPosition(t);
var s = t.scrollTop;
var val = t.value;
t.value = n > 0 ? val.slice(0 , p - n) val.slice(p):
val.slice(0, p) val.slice(p - n);
this.setCursorPosition(t ,p - (n < 0 ? 0 : n));
firefox=navigator.userAgent.toLowerCase().match(/firefox/([d.] )/) && setTimeout(function(){
if(t.scrollTop != s) t.scrollTop=s;
},10)
},
/*
* Select the text from s to z position
* @Method sel
* @param t element
* @param s number
* @param z number
* @return
*/
sel:function(t, s, z){
if(document.selection){
var range = t.createTextRange();
range.moveEnd('character', -t.value.length);
range.moveEnd('character', z);
range. moveStart('character', s);
range.select();
}else{
t.setSelectionRange(s,z);
t.focus();
}
},
/*
* Select a string
* @Method sel
* @param t element
* @param s String
* @return
* /
selString:function(t, s){
var index = t.value.indexOf(s);
index != -1 ? this.sel(t, index, index s.length) : false;
}
}