改进EXTJS的maxlength设置

在写Extjs3的时候，发现textfield输入框的maxlength设置之后不能限制输入的长度，只能在输入超出maxlength之后给出错误提示。
Google之后，发现可以把下段代码放入程序，一起加载就可以解决这个问题。

// To fix the maxlength property
// if the textfield sets {maxlength} property, it cannot be inputted more than {maxlength} characters.
// before fixing, the textfield can be inputted any amount of characters. When it lose focus, the validation messages will show.
Ext.form.TextField.prototype.size = 255;
Ext.form.TextField.prototype.initValue = function()
{
    if(this.value !== undefined){
        this.setValue(this.value);
    }else if(this.el.dom.value.length > 0){
        this.setValue(this.el.dom.value);
    }
    this.el.dom.size = this.size;
    if (!isNaN(this.maxLength) && (this.maxLength *1) > 0 && (this.maxLength != Number.MAX_VALUE)) {
        this.el.dom.maxLength = this.maxLength *1;
    }
};