考虑左位补0且规避掉空格的方法

  this.form.inputNum = (rule,value,callback) => {// 保单号码校验   左位补零&&去除空格
            var reg = /^[\d\s]+$/;
            if(!reg.test(value) && this.form.inputNum){
                    this.$message({
                        message : '请输入不超过15位数字',   
                        type : "error"
                    })
                this.form.inputNum = ''
            }else if(this.form.inputNum.length < 15 && this.form.inputNum.length){//输入数字不满15位，前面自动补0
                 var inputNum = this.form.inputNum.replace(/\s+/g,'')
                    var length = 15 - inputNum.length;
                    var str = '';
                    for(var i = 0; i < length; i++){
                        str = str + 0; 
                    }
                    this.form.inputNum = str +  inputNum;
            }else{
                callback()
            }
        };