blocks|key|37405|text|我以前经常这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|37406|var+my_var+=+<%25=+User.count+%25>
console.log(my_var)|code-block|syntax|javascript|37407|如果它是一个整数，那么它就可以正常工作。但是，如果您想要传递对象，则使用：|37408|var+my_var+=+JSON.parse(('<%25=+(@Users.count)+==+0+?+"[]"+:+Users.first(10).to_json+%25>')

console.log(JSON.stringify(my_var))|37409|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I used to do: 

<pre><code>var my_var = &lt;%= User.count %&gt;
console.log(my_var)
</code></pre>

If it is an integer this works just fine.
If, however, you want to pass objects, then use:

<pre><code>var my_var = JSON.parse(('&lt;%= (@Users.count) == 0 ? "[]" : Users.first(10).to_json %&gt;')

console.log(JSON.stringify(my_var))
</code></pre>

blocks|key|2716706|text|您忘记了文档就绪。尝试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2716707|$(function(){+
++var+datadump+=+($('#trackers').data('trackers'));
++console.log(datadump)
});|code-block|syntax|javascript|2716708|或者使用Gon+gem+https://github.com/gazay/gon从Rails向JS提供数据|offset|length|2716709|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/gazay/gon^0|0|0|C|S|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

You forgot about document ready. Try:

<pre><code>$(function(){ 
 var datadump = ($('#trackers').data('trackers'));
 console.log(datadump)
});
</code></pre>

Or for provide data from Rails to JS use Gon gem <a href="https://github.com/gazay/gon" rel="nofollow">https://github.com/gazay/gon</a>

blocks|key|2716729|text|从谷歌跌跌撞撞地来到这里。在我的例子中，我试图将一个对象数组传递给一个js.erb，它触发了一个前端组件侦听的事件。对于来自谷歌的任何人，我通过以下方法解决了这个问题：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2716730|在我的controller.rb中：|2716731|@payload+=+[]

array.each+do+%7Ca%7C
++temp+=+{
++++foo:+a.id,
++++bar:+a.relation.relation
++}
++@payload+<<+temp
end|code-block|syntax|javascript|2716732|在我的js.erb中：|2716733|$(document).trigger('event',+{+data:+<%25=+@payload.to_json.html_safe+%25>+})|2716734|在我的component.js中：|2716735|$(document).on('event',+(e,+data)+=>+{
++console.log(data)+//should+be+array+of+objects+in+proper+format
})|2716736|希望这对某些人有帮助！|2716737|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

Stumbled here from google. In my case, I was trying to pass an array of objects to a js.erb, which triggered an event a front end component listened to. For anyone from google, I solved this issue by doing the following:

In my controller.rb:

<pre><code>@payload = []

array.each do |a|
 temp = {
 foo: a.id,
 bar: a.relation.relation
 }
 @payload &lt;&lt; temp
end
</code></pre>

in my js.erb:

<pre><code>$(document).trigger('event', { data: &lt;%= @payload.to_json.html_safe %&gt; })
</code></pre>

in my component.js:

<pre><code>$(document).on('event', (e, data) =&gt; {
 console.log(data) //should be array of objects in proper format
})
</code></pre>

Hope this helps someone!

blocks|key|2716745|text|This可以帮助你。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2716746|对我来说，我想把这个数组|2716747|++@dates+=+["2018-12-24",+"2018-12-25",+"2018-12-26",+"2018-12-27",+"2018-12-28"]|code-block|syntax|javascript|2716748|转换为Javascript中的变量。我尝试了基本的：|2716749|var+dates+=+<%25=+@dates.join(",+")+%25>
alert(my_var)|2716750|这提醒了这个确切的文本：|2716751|1995|2716752|我不知道为什么。|2716753|由于它不工作，我尝试了Guru的解决方案，通过复制和粘贴，但现在更糟糕的是，我在我的代码中出现了一个错误。最后，我得到了Guru的解决方案，如下所示：|2716754|(嵌入ruby的print+open和close在JSON.parse()之外工作，缺少一个")“)|2716755|++var+dates+=+<%25=+JSON.parse(@dates.join(",+").to_json)%25>
++alert(dates)|2716756|但是，即使它没有崩溃，想猜猜它警告了什么吗？|2716757|是的，你猜对了：|2716758|2716759|所以我放弃了，我用了一个变通的办法：|2716760|在我看来，edit.html.erb|2716761|<div+class="dates"><%25=+@dates.join(",+")+%25></div>
<script>
++var+dates+=+$(".dates").text()
++alert(dates)
++$(".datepicker").val(dates)
</script>|2716762|这允许我提供变量，从而警告正确的数据，并使用正确的信息设置Datepicker的输入。我仍然因为不能解决1995年的洞的问题而受到困扰。如果有人能解释一下，我将不胜感激。希望这对你有帮助，并有一个伟大的一天！|2716763|entityMap|0|LINK|mutability|MUTABLE|url|https://www.quora.com/How-do-I-pass-a-Ruby-variable-to-JavaScript^0|0|4|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1L|8|@]|9|@$A|1M|B|1N|1|1O]]|C|$]]|$1|D|3|E|5|6|7|1P|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|1Q|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|1R|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|1S|8|@]|9|@]|C|$I|J]]|$1|O|3|P|5|6|7|1T|8|@]|9|@]|C|$]]|$1|Q|3|R|5|H|7|1U|8|@]|9|@]|C|$I|J]]|$1|S|3|T|5|6|7|1V|8|@]|9|@]|C|$]]|$1|U|3|V|5|6|7|1W|8|@]|9|@]|C|$]]|$1|W|3|X|5|6|7|1X|8|@]|9|@]|C|$]]|$1|Y|3|Z|5|H|7|1Y|8|@]|9|@]|C|$I|J]]|$1|10|3|11|5|6|7|1Z|8|@]|9|@]|C|$]]|$1|12|3|13|5|6|7|20|8|@]|9|@]|C|$]]|$1|14|3|R|5|H|7|21|8|@]|9|@]|C|$I|J]]|$1|15|3|16|5|6|7|22|8|@]|9|@]|C|$]]|$1|17|3|18|5|6|7|23|8|@]|9|@]|C|$]]|$1|19|3|1A|5|H|7|24|8|@]|9|@]|C|$I|J]]|$1|1B|3|1C|5|6|7|25|8|@]|9|@]|C|$]]|$1|1D|3|-4|5|6|7|26|8|@]|9|@]|C|$]]]|1E|$1F|$5|1G|1H|1I|C|$1J|1K]]]]

<a href="https://www.quora.com/How-do-I-pass-a-Ruby-variable-to-JavaScript" rel="nofollow noreferrer">This</a> could help you. 

For me, I wanted to turn this array

<pre><code> @dates = ["2018-12-24", "2018-12-25", "2018-12-26", "2018-12-27", "2018-12-28"]
</code></pre>

into a variable in Javascript. I tried the basic:

<pre><code>var dates = &lt;%= @dates.join(", ") %&gt;
alert(my_var)
</code></pre>

This alerted this exact text:

<pre><code>1995
</code></pre>

I have no clue why.

Since it wasn't working I tried Guru's solutions up there by copying and pasting, but it was worse now I had an error coming up in my code. Finally I got Guru's solution to work like this:

(the print embedded ruby open and close worked outside the JSON.parse() and there was a missing ")" )

<pre><code> var dates = &lt;%= JSON.parse(@dates.join(", ").to_json)%&gt;
 alert(dates)
</code></pre>

But even though it didn't crash, want to guess what it alerted?

Yeap, you guessed it:

<pre><code>1995
</code></pre>

So I gave up and I used a work around:

In my view edit.html.erb

<pre><code>&lt;div class="dates"&gt;&lt;%= @dates.join(", ") %&gt;&lt;/div&gt;
&lt;script&gt;
 var dates = $(".dates").text()
 alert(dates)
 $(".datepicker").val(dates)
&lt;/script&gt;
</code></pre>

That allowed me to feed the variable, therefore alert the correct data and set the Datepicker's input with the correct information. I'm still bugged for not being able to solve the hole 1995 problem. If someone could be so kind as to explain, I would really appreciate it. Hope this helps and have a great day!

I've tried numerous methods and followed <a href="http://railscasts.com/episodes/324-passing-data-to-javascript" rel="noreferrer">Ryan Bates'</a> guide but no matter what I do I still get undefined.

application.html.erb

<pre><code>&lt;body&gt;
 &lt;%= content_tag :div, id: 'trackers', data: {trackers: User.count} do %&gt;
 &lt;% end %&gt;
&lt;/body
</code></pre>

application.js.erb

<pre><code>var datadump = ($('#trackers').data('trackers'))
console.log(datadump)
//returns undefined in console
</code></pre>

Viewing page source I can see the variable

<pre><code>&lt;div data-trackers="2" id="trackers"&gt;
</code></pre>

I'm passing User.count for now just to keep it simple but I'll need to be passing @trackers_count which is instantiated in a before_action in the application controller. I should be able to sort that out though once I figure out the problem here. Any suggestions?

UPDATE - I've simplified all variables down to just trackers, instead of trackers_count to prevent any errors from syntax and updated code here to reflect that.

ANSWER UPDATE - I selected the correct answer because if you want to pass any variables ASIDE FROM CURRENT_USER those methods worked perfectly. However, you can't access anything with current_user in JS because it loads before the window, so it can't know who the current_user is. It's a real pain but I just did it the long way and accessed the info I need through passing in json and an ajax requests.

Rails 4: Passing variables to javascript

JSON

我尝试了许多方法，并遵循指南，但无论我做什么，我仍然没有定义。application.html.erb<body> <%= content_tag :div, id: 'trackers', data: {trackers: User.count} do %> <% end %></bodyapplication.js...

问Rails 4:将变量传递给javascript
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