function eqa(obj,nu){
var oPa = document.getElementById(obj);
var sto = oPa.innerHTML;
if (sto.length>nu) {
oPa.innerHTML = sto.substring(0, nu)+‘......‘;
} else{
oPa.innerHTML=sto;
};
}
原文：http://www.cnblogs.com/saoniansaonian/p/6848122.html