Angular6 - 如何正确验证和不接受空输入字段

Question

我正在使用 Angular 并试图弄清楚如何正确验证输入字段并且它不应该接受空格。我尝试使用如下所示的 IF 语句 对其进行试验。它似乎工作正常，但当一个输入字段为空白时，我收到此错误消息:

ERROR TypeError: formValue.employee.trim is not a function

onSubmit() { //when  the user clicks the submit button
 const formValue = this.telephoneForm.value;
 this.submitted = true;
  if (this.telephoneForm.invalid) {
   const invalidControls = this._findInvalidControls();
    if (invalidControls.length) {
    $("[formControlName=" + invalidControls[0] + "]").focus();
   }
 }

 if (
   this.telephoneForm.invalid ||
   this.alreadyExist ||
   this.noEmployeesFound ||
   this.noDepartmentsFound ||
   this.noVendorsFound
 ) {
   return;
 }


 if (
  (formValue["department"] === null ||
  formValue["department"].trim() === "") ||
  formValue["employee"] === null ||
  formValue["employee"].trim() === "" ||
  formValue["vendor"] === null ||
  formValue["vendor"].trim() === ""
 ) {
  $("[formControlName='department']").focus();
  $("[formControlName='employee']").focus();
  $("[formControlName='vendor']").focus();

  this.noEmployeesFound = true;
  this.noDepartmentsFound = true;
  this.noVendorsFound = true;

  return false;
 }
}

看这个 screenshot of the form where I use this code

Answer 1

试试这个。

formValue.employee.toString().trim()