element-plus/docs/examples/form/custom-validation.vue

<template>
  <el-form
    ref="ruleForm"
    :model="ruleForm"
    status-icon
    :rules="rules"
    label-width="120px"
    class="demo-ruleForm"
  >
    <el-form-item label="Password" prop="pass">
      <el-input
        v-model="ruleForm.pass"
        type="password"
        autocomplete="off"
      ></el-input>
    </el-form-item>
    <el-form-item label="Confirm" prop="checkPass">
      <el-input
        v-model="ruleForm.checkPass"
        type="password"
        autocomplete="off"
      ></el-input>
    </el-form-item>
    <el-form-item label="Age" prop="age">
      <el-input v-model.number="ruleForm.age"></el-input>
    </el-form-item>
    <el-form-item>
      <el-button type="primary" @click="submitForm('ruleForm')"
        >Submit</el-button
      >
      <el-button @click="resetForm('ruleForm')">Reset</el-button>
    </el-form-item>
  </el-form>
</template>

<script lang="ts">
export default {
  data() {
    const checkAge = (rule, value, callback) => {
      if (!value) {
        return callback(new Error('Please input the age'))
      }
      setTimeout(() => {
        if (!Number.isInteger(value)) {
          callback(new Error('Please input digits'))
        } else {
          if (value < 18) {
            callback(new Error('Age must be greater than 18'))
          } else {
            callback()
          }
        }
      }, 1000)
    }
    const validatePass = (rule, value, callback) => {
      if (value === '') {
        callback(new Error('Please input the password'))
      } else {
        if (this.ruleForm.checkPass !== '') {
          this.$refs.ruleForm.validateField('checkPass')
        }
        callback()
      }
    }
    const validatePass2 = (rule, value, callback) => {
      if (value === '') {
        callback(new Error('Please input the password again'))
      } else if (value !== this.ruleForm.pass) {
        callback(new Error("Two inputs don't match!"))
      } else {
        callback()
      }
    }
    return {
      ruleForm: {
        pass: '',
        checkPass: '',
        age: '',
      },
      rules: {
        pass: [{ validator: validatePass, trigger: 'blur' }],
        checkPass: [{ validator: validatePass2, trigger: 'blur' }],
        age: [{ validator: checkAge, trigger: 'blur' }],
      },
    }
  },
  methods: {
    submitForm(formName) {
      this.$refs[formName].validate((valid) => {
        if (valid) {
          alert('submit!')
        } else {
          console.log('error submit!!')
          return false
        }
      })
    },
    resetForm(formName) {
      this.$refs[formName].resetFields()
    },
  },
}
</script>