不能以小数点开头，且只能有一个小数点

<el-input  v-model="input" :oninput=" input = inputNum(input)"  />

setup(){
 const input = Vue.ref(undefined)
 const inputNum = (value) => {
      if (value == undefined) return;
      return value
        .replace(/[^\d.]/g, "")
        .replace(/\.{2,}/g, ".")
        .replace(".", "$#$")
        .replace(/\./g, "")
        .replace("$#$", ".")
        .replace(/^\./g, "");
    }
    
   return {
 	value,
 	inputNum 
 }
}