onkey 事件

onkeyup="this.value=this.value.replace(/[^0-9]+/,'');"  //只能输入数字

onkeyup="this.value=this.value.replace(/^[0]{1}[0-9]*$/,'')"； //首字母不能输入0

oninput='this.value=this.value.replace(/^[0]*$/gi,"")'//0输入不了

onkeyup="this.value=this.value.replace(/^ +| +$/g,'')"//不能输入空格

onkeyup="if (this.value.length == 1) { this.value = this.value.replace(/[^0-9]/g, '') } else { this.value = this.value.replace(/\D/g, '').replace(/^0+/g, '') }" onafterpaste="if (this.value.length == 1) { this.value = this.value.replace(/[^0-9]/g, '') } else { this.value = this.value.replace(/^0+/g, '')" //首字母可以输入0,正整数，去除空格