Javascript 表单验证在使用java脚本的codeigniter中不起作用

我正在使用java脚本开发Codeigniter和验证表单 我的视图文件是

<div class="container">
    <div class="limiter">
        <div class="container-login100">
            <div class="wrap-login100 p-l-55 p-r-55 p-t-65 p-b-50" >
                <form class="login100-form" action="<?php echo base_url('index.php/Customer/addCustomer') ?>" method="post">
                    <h2 class="login100-form-title p-b-33"> Add Admin </h2>

                      <div class="form-group ">
                        <label class="control-label col-md-2 col-sm-6 col-xs-12" >First Name:</label>
                        <input class="input100" type="text"  id="first_name" placeholder="Enter first_name" name="first_name"/>
                        <span id="errorfirstname"></span>
                    </div>

                    <div class="container-login100-form-btn m-t-20">
                        <input type="submit" class="btn btn-dark login100-form-btn" id="save" name="save" value="Save" onclick="validation()"/>
                    </div>
                </form>
            </div>
        </div>
    </div>
</div>

java脚本代码是

function validation() {
    if (document.getElementById("first_name").value == "") {
        var str = ("First Name may not be blank");
        document.getElementById("errorfirstname").innerHTML = str;
    } else if (document.getElementById("first_name") != /^[a-zA-Z ]*$/) {
        var str = ("Please Enter Only Characters in First name");
    } else if (document.getElementById("first_name")) {
        var inpObj = document.getElementById("first_name");
        if (inpObj.value.length <= 30 && inpObj.value.length >= 3) {
            var str = ("Please Type Minmum 3 Characters Maximum 30 Characters ");
            document.getElementById("errorfirstname").innerHTML = str;
        }
    } else {
        var str = "Input is Not valid";
        document.getElementById("errorfirstname").innerHTML = str;
    }
}

我的实际问题是，当我提交表单时，它在验证后将在javascript上运行，它不返回错误，但它将在控制器文件上运行。如果验证失败，请在查看页面上返回，而不是在控制器上运行。

如果验证未通过，则必须在验证时返回false。onclick中还缺少一个return语句。它应该像onclick=returnvalidation那样调用验证

有关详细信息，请参阅此处：

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不过，我建议您使用现成的解决方案，如或。它们经过了尝试和测试，涵盖了我们容易忘记的大多数关键案例，得到了数百名其他开发人员的批准，并节省了开发时间。

请在表单标签中添加表单id作为“表单id”。并使用下面的解决方案

document.querySelector("#form-id").addEventListener('submit', (e) => {
    //prevent actual submit
    e.preventDefault();

    //Get form values
    const first_name = document.querySelector("#first_name").value;

    const errorfirstname = document.querySelector("#errorfirstname");
    const letters = /^[a-zA-Z ]*$/;

    if (first_name === "") {
        errorfirstname.className = "alert alert-danger";
        errorfirstname.innerHTML = "First Name may not be blank";
    } else if (!first_name.match(letters)) {
        errorfirstname.className = "alert alert-danger";
        errorfirstname.innerHTML = "Please Enter Only Characters in First name";
    } else if (first_name.length < 3 || first_name.length > 30) {
        errorfirstname.className = "alert alert-danger";
        errorfirstname.innerHTML = "Please Type Minmum 3 Characters Maximum 30 Characters";
    } else {
        e.submit();
    }
});

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如果出现错误，则需要添加return false以阻止默认表单操作，即提交表单。

document.querySelector("#form-id").addEventListener('submit', (e) => {
    //prevent actual submit
    e.preventDefault();

    //Get form values
    const first_name = document.querySelector("#first_name").value;

    const errorfirstname = document.querySelector("#errorfirstname");
    const letters = /^[a-zA-Z ]*$/;

    if (first_name === "") {
        errorfirstname.className = "alert alert-danger";
        errorfirstname.innerHTML = "First Name may not be blank";
    } else if (!first_name.match(letters)) {
        errorfirstname.className = "alert alert-danger";
        errorfirstname.innerHTML = "Please Enter Only Characters in First name";
    } else if (first_name.length < 3 || first_name.length > 30) {
        errorfirstname.className = "alert alert-danger";
        errorfirstname.innerHTML = "Please Type Minmum 3 Characters Maximum 30 Characters";
    } else {
        e.submit();
    }
});