正则表达式 //只能输入两个小数

obj.value = obj.value.replace(/^(-)(\d+).(\d\d).$/,'$1$2.$3');
改成只能输入四位小数

let obj={"value":"-34.45678930"};
obj.value = obj.value.replace(/^(-)(\d+).(\d{4})(\d+)/,'$1$2.$3');
console.log(obj.value);// 输出 -34.4567

前端有toFixed(x)可以限制