文本域字数限制

textarea限制输入字数(例：最大输入字数100)

<input type='textarea' maxlength="100" onKeyDown='if (this.value.length>=100){this.value=this.value.substring(0,100)}' />

<textarea maxlength="100" onKeyDown='if (this.value.length>=100){this.value=this.value.substring(0,100)}'></textarea>