Using Rails and Haml to Implement Smooth Scrolling with Jquery and CoffeeScript

Question

Using Rails and Haml to Implement Smooth Scrolling with Jquery and CoffeeScript

Looking to accomplish a straightforward task using CoffeeScript, Rails, and Haml. While I don't have much experience with CoffeeScript, I'm eager to experiment.

The goal is to have the view scroll to a specific div id when a button is pressed. At the top of my page, there's an Id set up like this:

#area_1

My links are structured as follows:

= link_to "Area", "#", id: "area_button_1"

In my auto-generated CoffeScript file, there's a function defined as:

$ ->
  scrollToArea = (button, area) ->
    $(button).click ->
      scrollTo(area, 800)

Attempting to invoke this method in one of my view files like so:

:javascript
  scrollToArea("#area_button_1", "#area_1")

However, it seems to not be functioning as expected. Any insights on what might be causing the issue?

javascript jquery ruby-on-rails coffeescript haml

Answer 1

Answer №1

It seems like there may be a scoping issue at play here. The $ -> is essentially a function call similar to:

$(function() { ...
});

CoffeeScript automatically manages variable scopes within functions, so your CoffeeScript code translates to JavaScript like this:

$(function() {
  var scrollToArea = function(button, area) { ... };
});

There's also an additional self-executing function wrapper around the entire block (unless you compile with -b) in order to prevent scope issues.

In this context, the $ -> isn't necessary as it only defines a function that can run at any time, regardless of DOM readiness. If you intend to use scrollToArea elsewhere, consider placing it in the global namespace, like so:

window.scrollToArea = (button, area) ->
  $(button).click ->
    scrollTo(area, 800)

Alternatively:

# In this scenario, `this` represents `window`, making `@x` equivalent to `window.x`
@scrollToArea = (button, area) ->
  $(button).click ->
    scrollTo(area, 800)

When using scrollToArea, it's advised to wrap it within a $() function to ensure it runs only when the DOM is ready:

:javascript
  $(function() { scrollToArea("#area_button_1", "#area_1") )

As I'm not well-versed in HAML syntax, I hope I've correctly conveyed the information.

Answer 2

It seems like there may be a scoping issue at play here. The $ -> is essentially a function call similar to:

$(function() { ...
});

CoffeeScript automatically manages variable scopes within functions, so your CoffeeScript code translates to JavaScript like this:

$(function() {
  var scrollToArea = function(button, area) { ... };
});

There's also an additional self-executing function wrapper around the entire block (unless you compile with -b) in order to prevent scope issues.

In this context, the $ -> isn't necessary as it only defines a function that can run at any time, regardless of DOM readiness. If you intend to use scrollToArea elsewhere, consider placing it in the global namespace, like so:

window.scrollToArea = (button, area) ->
  $(button).click ->
    scrollTo(area, 800)

Alternatively:

# In this scenario, `this` represents `window`, making `@x` equivalent to `window.x`
@scrollToArea = (button, area) ->
  $(button).click ->
    scrollTo(area, 800)

When using scrollToArea, it's advised to wrap it within a $() function to ensure it runs only when the DOM is ready:

:javascript
  $(function() { scrollToArea("#area_button_1", "#area_1") )

As I'm not well-versed in HAML syntax, I hope I've correctly conveyed the information.

Answer 3

Answer №2

I have limited experience with coffeeScript, but I can provide you with the jQuery code to achieve the same result. You may find it easy to translate.

This code sets the window's scrollTop equal to the top position of the target element using offset().

<a href="#button" class="scroll-trigger">Go to button</a>

$('.scroll-trigger').click(function() {
    $(window).scrollTop($(this).attr('href')).offset().top);
});

Example fiddle

If you prefer an animated scrolling effect, you can use this code:

$('.scroll-trigger').click(function() {
    var $el = $(this);
    $('html, body').animate({
        scrollTop: $($el.attr('href')).offset().top
    }, 2000);
});

Example fiddle

Answer 4

I have limited experience with coffeeScript, but I can provide you with the jQuery code to achieve the same result. You may find it easy to translate.

This code sets the window's scrollTop equal to the top position of the target element using offset().

<a href="#button" class="scroll-trigger">Go to button</a>

$('.scroll-trigger').click(function() {
    $(window).scrollTop($(this).attr('href')).offset().top);
});

Example fiddle

If you prefer an animated scrolling effect, you can use this code:

$('.scroll-trigger').click(function() {
    var $el = $(this);
    $('html, body').animate({
        scrollTop: $($el.attr('href')).offset().top
    }, 2000);
});

Example fiddle

Using Rails and Haml to Implement Smooth Scrolling with Jquery and CoffeeScript

Answer №1

Answer №2

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