如何使用JavaScript在HTML的textArea上施加maxlength

window.onload = function() {
var txts = document.getElementsByTagName(‘textarea’);

  for(var i = 0, l = txts.length; i < l; i++) {    if(/^[0-9]+$/.test(txts[i].getAttribute("maxlength"))) {       var func = function() {         var len = parseInt(this.getAttribute("maxlength"), 10);        if(this.value.length > len) {alert('Maximum length exceeded: ' + len);this.value = this.value.substr(0, len);return false;         }       }      txts[i].onkeyup = func;      txts[i].onblur = func;    }   };}