Element form sheet method resetFields invalid

ResetFields invalid before the face of his or her own hand with this.ruleForm = Object.assign ({}, this.ruleForm , this. $ Options.data (). RuleForm) to clear the data in this way, with such a long form form, resetFields really take effect sometimes and sometimes not in force, then looked under the Element source, and finally found the mystery
source form-item when mounted is so written

mounted() {
      if (this.prop) {
        this.dispatch('ElForm', 'el.form.addField', [this]);

        let initialValue = this.fieldValue;
        if (Array.isArray(initialValue)) {
          initialValue = [].concat(initialValue);
        }
        Object.defineProperty(this, 'initialValue', {
          value: initialValue
        });

        this.addValidateEvents();
      }
    },

We can see the whole mounted operations are based on your definition of the prop can, then that is the definition of a initialValue initial value, and put in under this, and then execute resetFields when the value becomes the initial value, so the future appears to be necessary to prop Defined