html 只能输入固定长度数字

    <input  id="testPaperBuyBoxes" name="testPaperBuyBoxes"  maxlength="3" type="text"
                                               onkeyup="if(this.value.length==1){this.value=this.value.replace(/[^1-9]/g,'')}else{this.value=this.value.replace(/\D/g,'')}"
                                               onafterpaste="if(this.value.length==1){this.value=this.value.replace(/[^1-9]/g,'')}else{this.value=this.value.replace(/\D/g,'')}"
                                        />

maxlength=”3” type=”text”