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Diffstat (limited to 'guides/source/working_with_javascript_in_rails.md')
| -rw-r--r-- | guides/source/working_with_javascript_in_rails.md | 66 |
1 files changed, 34 insertions, 32 deletions
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md index 0f5acfba3c..a7ca531123 100644 --- a/guides/source/working_with_javascript_in_rails.md +++ b/guides/source/working_with_javascript_in_rails.md @@ -66,37 +66,38 @@ Here's the simplest way to write JavaScript. You may see it referred to as 'inline JavaScript': ```html -<a href="#" onclick="alert('Hello, world.')">Here</a> +<a href="#" onclick="this.style.backgroundColor='#990000'">Paint it red</a> ``` - -When clicked, the alert will trigger. Here's the problem: what happens when -we have lots of JavaScript we want to execute on a click? +When clicked, the link background will become red. Here's the problem: what +happens when we have lots of JavaScript we want to execute on a click? ```html -<a href="#" onclick="function fib(n){return n<2?n:fib(n-1)+fib(n-2);};alert('fib of 15 is: ' + fib(15) + '.');">Calculate</a> +<a href="#" onclick="this.style.backgroundColor='#009900';this.style.color='#FFFFFF';">Paint it green</a> ``` Awkward, right? We could pull the function definition out of the click handler, and turn it into CoffeeScript: ```coffeescript -fib = (n) -> - (if n < 2 then n else fib(n - 1) + fib(n - 2)) +paintIt = (element, backgroundColor, textColor) -> + element.style.backgroundColor = backgroundColor + if textColor? + element.style.color = textColor ``` And then on our page: ```html -<a href="#" onclick="alert('fib of 15 is: ' + fib(15) + '.');">Calculate</a> +<a href="#" onclick="paintIt(this, '#990000')">Paint it red</a> ``` That's a little bit better, but what about multiple links that have the same effect? ```html -<a href="#" onclick="alert('fib of 16 is: ' + fib(16) + '.');">Calculate</a> -<a href="#" onclick="alert('fib of 17 is: ' + fib(17) + '.');">Calculate</a> -<a href="#" onclick="alert('fib of 18 is: ' + fib(18) + '.');">Calculate</a> +<a href="#" onclick="paintIt(this, '#990000')">Paint it red</a> +<a href="#" onclick="paintIt(this, '#009900', '#FFFFFF')">Paint it green</a> +<a href="#" onclick="paintIt(this, '#000099', '#FFFFFF')">Paint it blue</a> ``` Not very DRY, eh? We can fix this by using events instead. We'll add a `data-*` @@ -104,19 +105,21 @@ attribute to our link, and then bind a handler to the click event of every link that has that attribute: ```coffeescript -fib = (n) -> - (if n < 2 then n else fib(n - 1) + fib(n - 2)) - -$(document).ready -> - $("a[data-fib]").click (e) -> - count = $(this).data("fib") - alert "fib of #{count} is: #{fib(count)}." - -... later ... - -<a href="#" data-fib="15">Calculate</a> -<a href="#" data-fib="16">Calculate</a> -<a href="#" data-fib="17">Calculate</a> +paintIt = (element, backgroundColor, textColor) -> + element.style.backgroundColor = backgroundColor + if textColor? + element.style.color = textColor + +$ -> + $("a[data-color]").click -> + backgroundColor = $(this).data("background-color") + textColor = $(this).data("text-color") + paintIt(this, backgroundColor, textColor) +``` +```html +<a href="#" data-background-color="#990000">Paint it red</a> +<a href="#" data-background-color="#009900" data-text-color="#FFFFFF">Paint it green</a> +<a href="#" data-background-color="#000099" data-text-color="#FFFFFF">Paint it blue</a> ``` We call this 'unobtrusive' JavaScript because we're no longer mixing our @@ -204,7 +207,7 @@ is a helper that assists with generating links. It has a `:remote` option you can use like this: ```erb -<%= link_to "first post", @post, remote: true %> +<%= link_to "a post", @post, remote: true %> ``` which generates @@ -214,20 +217,19 @@ which generates ``` You can bind to the same Ajax events as `form_for`. Here's an example. Let's -assume that we have a resource `/fib/:n` that calculates the `n`th Fibonacci -number. We would generate some HTML like this: +assume that we have a list of posts that can be deleted with just one +click. We would generate some HTML like this: ```erb -<%= link_to "Calculate", "/fib/15", remote: true, data: { fib: 15 } %> +<%= link_to "Delete post", @post, remote: true, method: :delete %> ``` and write some CoffeeScript like this: ```coffeescript -$(document).ready -> - $("a[data-fib]").on "ajax:success", (e, data, status, xhr) -> - count = $(this).data("fib") - alert "fib of #{count} is: #{data}." +$ -> + $("a[data-remote]").on "ajax:success", (e, data, status, xhr) -> + alert "The post was deleted." ``` ### button_to |