Submitting a form using AJAX

You can check out the AJAX example inside the Demo templates included with Express Forms. Below is an example from it.

TIP

For no-fuss AJAX control built right into your forms, you may want to consider Freeform.

Place something like the following at your page footer:

<script>
  var safari = navigator.userAgent.indexOf("Safari") > -1

  function ajaxifyForm(event) {
    var form = event.target
    var data = new FormData(form)
    var request = new XMLHttpRequest()

    if (safari) {
      for (var i = 0; i < form.elements.length; i++) {
        if (form.elements[i].type == "file") {
          if (form.elements[i].value == "") {
            var elem = form.elements[i]
            data.delete(elem.name)
          }
        }
      }
    }

    var method = form.getAttribute("method")
    var action = form.getAttribute("action")

    request.open(method, action ? action : window.location.href, true)
    request.setRequestHeader("Cache-Control", "no-cache")
    request.setRequestHeader("X-Requested-With", "XMLHttpRequest")
    request.setRequestHeader("HTTP_X_REQUESTED_WITH", "XMLHttpRequest")
    request.onload = function() {
      removeMessages(form)

      if (request.status === 200) {
        var response = JSON.parse(request.response)

        if (response.success) {
          // Reset the form so that the user may enter fresh information
          form.reset()

          // ============================================================
          // Uncomment this to have the form redirect to the success page
          // ============================================================
          // if (response.return) {
          //   window.location.href = response.return;
          // }

          renderFormSuccess(form)

        } else if (response.errors || response.formErrors) {
          renderErrors(response.errors, form)
          renderFormErrors(response.formErrors, form)
        }

        replaceInputs(form, response);
        unlockSubmit(form)
      } else {
        console.error(request)
      }

      unlockSubmit(form)
    }

    request.send(data)
    event.preventDefault()
  }

  function replaceInputs(form, response) {
    if (response.duplicateCheck) {
      var prefix = response.duplicateCheck.prefix;
      var value = response.duplicateCheck.value;
      var input = form.querySelector('input[name^="' + prefix + '"]');
      if (input) {
        input.setAttribute("name", value);
        input.setAttribute("value", value);
      }
    }
  }

  /**
    * Remove the "disabled" state of the submit button upon successful submit
    *
    * @property form
    */
  function unlockSubmit(form) {
    form.querySelector("button[type=submit]").removeAttribute("disabled")
    if (typeof grecaptcha !== "undefined") {
      grecaptcha.reset()
    }
  }

  function removeMessages(form) {
    // Remove error messages
    form.querySelectorAll("ul.errors").remove()
    var fieldsWithErrors = form.querySelectorAll(".has-error")
    for (var fieldIndex = 0; fieldIndex < fieldsWithErrors.length; fieldIndex++) {
      fieldsWithErrors[fieldIndex].classList.remove("has-error")
    }

    // Remove success messages
    form.querySelectorAll(".form-success").remove()
    document.getElementsByClassName("form-errors").remove()
  }

  function renderFormSuccess(form) {
    var successMessage = document.createElement("div")
    successMessage.classList.add("alert", "alert-success", "form-success")

    successMessage.appendChild(
      document.createTextNode("Form has been submitted successfully!")
    )

    form.insertBefore(successMessage, form.childNodes[0])
  }

  function renderErrors(errors, form) {
    for (var key in errors) {
      if (!errors.hasOwnProperty(key) || !key) {
        continue
      }

      var messages = errors[key]
      var errorsList = document.createElement("ul")
      errorsList.classList.add("errors")

      for (var messageIndex = 0; messageIndex < messages.length; messageIndex++) {
        var message = messages[messageIndex]
        var listItem = document.createElement("li")
        listItem.appendChild(document.createTextNode(message))
        errorsList.appendChild(listItem)
      }

      var inputList = form.querySelectorAll("*[name=" + key + "], *[name='" + key + "[]']")
      for (var inputIndex = 0; inputIndex < inputList.length; inputIndex++) {
        var input = inputList[inputIndex]

        input.findAncestor("form-group").classList.add("has-error")
        input.findAncestor("form-group").appendChild(errorsList)
      }
    }
  }

  function renderFormErrors(errors, form) {
    var errorBlock = document.createElement("div")
    errorBlock.classList.add("alert", "alert-danger", "form-errors")

    errorBlock.appendChild(
      document.createTextNode("Error! Please review the form and try submitting again.")
    )

    if (errors.length) {
      var errorsList = document.createElement("ul")
      for (var messageIndex = 0; messageIndex < errors.length; messageIndex++) {
        var message = errors[messageIndex]
        var listItem = document.createElement("li")

        listItem.appendChild(document.createTextNode(message))
        errorsList.appendChild(listItem)
      }

      errorBlock.appendChild(errorsList)
    }

    form.insertBefore(errorBlock, form.childNodes[0])
  }

  // Add remove prototypes
  Element.prototype.remove = function() {
    this.parentElement.removeChild(this)
  }

  Element.prototype.findAncestor = function(className) {
    let el = this
    while (!el.classList.contains(className)) {
      el = el.parentElement
    }

    return el
  }

  NodeList.prototype.remove = HTMLCollection.prototype.remove = function() {
    for (var i = this.length - 1; i >= 0; i--) {
      if (this[i] && this[i].parentElement) {
        this[i].parentElement.removeChild(this[i])
      }
    }
  }

  document.getElementById("ajax-form").addEventListener("submit", ajaxifyForm)
</script>
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And be sure to assign a matching ID attribute to your form (e.g. ajax-form is used above) to the form.openTag():

{{ form.openTag({
    return: '?success=1',
    attributes: {
        id: "ajax-form",
    },
}) }}
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Last Updated: 5/8/2019, 2:29:45 PM