我的JQuery验证错误(Error in my JQuery validation)

 你好，我在我的jquery验证错误，代码不做任何事，任何人都可以帮助我吗？ 
 
<script>

    // When the user submits the form,
    //   Check what answer they picked
    //   And tell them if they're correct

    // submit
    $("#form").on("submit", function(event) {
        event.preventDefault();
        var $answer = $("#unit_name"); 
        var answer = $answer.val();
        console.log(answer);
        if (answer === "") {
            $("#result").text("Preencha corretamente o nome da unidade.");
        } else if(answer.length < 3 ) {
            $("#result").text("O nome da unidade é demasiado pequeno.");
        }

    });
    </script>
 
 
 这是实施表单的代码 
 
                     <div class="pure-u-1">
                        <h3 align="center">Insert</h3>
                        </div>




                     <div class="form-group">
        <label class="control-label" for="unit_name"Name concept:</label>
        <div class="input-group">
            <input class="form-control" placeholder="Insert name" id="unit_name" name="unit_name" type="text" />
        </div>
    </div>
                        <input type="hidden" name="state" value="insert">
                        <input type="submit" value="Insert">
                        <br><br>
                    </div>

            </form>
 
 这个div将向用户显示消息。 

Hello i have error in my Jquery validation, the code dont do nothing, can anybody help me?
 
<script>

    // When the user submits the form,
    //   Check what answer they picked
    //   And tell them if they're correct

    // submit
    $("#form").on("submit", function(event) {
        event.preventDefault();
        var $answer = $("#unit_name"); 
        var answer = $answer.val();
        console.log(answer);
        if (answer === "") {
            $("#result").text("Preencha corretamente o nome da unidade.");
        } else if(answer.length < 3 ) {
            $("#result").text("O nome da unidade é demasiado pequeno.");
        }

    });
    </script>
 
 
This is the code of the form implemented 
 
                     <div class="pure-u-1">
                        <h3 align="center">Insert</h3>
                        </div>




                     <div class="form-group">
        <label class="control-label" for="unit_name"Name concept:</label>
        <div class="input-group">
            <input class="form-control" placeholder="Insert name" id="unit_name" name="unit_name" type="text" />
        </div>
    </div>
                        <input type="hidden" name="state" value="insert">
                        <input type="submit" value="Insert">
                        <br><br>
                    </div>

            </form>
 
This div will show message to the users. 

原文：https://stackoverflow.com/questions/41681460