Git: Show commits that have touched specific text in a file
If you want to find the commits that touched a specific text in a file, use git log -S 'text in the code' -- path/to/file.
Here is an example, where the move of the convert_number_column_value(value) method in active record is traced (simplified output):
git log -n 1 --pretty=oneline -S 'convert_number_column_value(value)' -- activerecord/lib/active_record/base.rb
ceb33f84933639d3b61aac62e5e71fd087ab65ed Split out most of the AR::Base code into separate modules :cake:
```
git show ceb33f84933639d3b61aac62e5e71fd087ab65ed…
Finding a method name on a Ruby object
Wondering how a specific method on an object is exactly named? You can use Enumerable#grep to detect it in the array of methods.
@user.methods.grep /name/ # => [:name, :first_name, :last_name]
You can also call #private_methods or #public_methods. To find only relevant methods, it is suggested to subtract generic methods like this:
User.methods - Object.methods
User.methods - ActiveRecord::Base.methods
@user.methods - Object.instance_methods
@user.methods - ActiveRecord::Base.instance_methods
Using regular expressions in JavaScript
Regular expressions in Javascript are represented by a RegExp object. There also is a regex literal as in many other languages: /regex/. However, they are used slightly differently.
Regex literal
- Usage:
/foo+/ - Shorthand for creating a regular expression object
RegExp() object
- Usage:
Regexp("foo+")ornew RegExp("foo+") - No surrounding slashes required (they're the literal markers)
- Since the argument is a string, backslashes need to be escaped as well:
RegExp("\\d+")
Gotchas
- Regex objects [never eq…
no passenger served applications running error when deploying via capistrano
When deploying with capistrano it's possible you get this "error" message:
*** [err :: example.com] There are no Phusion Passenger-served applications running whose paths begin with '/var/www/example.com'.
*** [err :: example.com]
This is just because there were no running passenger process for this application on the server which could be restarted. It's not a real error. The application process will start if the first request for this app hits the appserver.
The output appears as err because it's printed to stderr.
Dep…
z-index: About stacking contexts
The CSS property z-index is not as global as you might believe. Actually, it is scoped to a so-called "stacking context". z-indexes only have meaning within their stacking context, while stacking contexts are treated as a single unit in their parent stacking context. This means indices like 99999 should never actually be needed.
Creating a new stacking context
In order to create a stacking context with the least possible side effects, use these properties on an element:
```
position: relative // or absolute
z-index: 0 // o…
Stop animations and network polling when the document tab isn't visible
Is your application doing something expensive every few seconds? Maybe an animated slider that rotates images? Maybe you are updating data over the network every five minutes?
It's a good idea to pause this if the your document tab is not even visible to the user. This saves your user's battery and data plan.
You can ask document.visibilityState whether this tab is visible:
```
function pulse() {
if (!document.visibilityState || document.visibilityState =…
Execution of shell code in Ruby scripts
Deprecated ways to execute shell code in Ruby
This is just a reference for legacy code. For new code, always use capture3.
%x{ } or backticks – quick and easy
Returns the standard output of running the given command in a subshell. This is an alias for `…`, and you can use string interpolation.
Example:
name = 'ls'
result = `which #{name}`
It does not escape anything you inject in the string.
If you want to find out if the call was …
How to install npm packages globally without sudo on Linux
All quoted.
-
Set up a package root in your homedir to hold the Node "global" packages:
$ NPM_PACKAGES="$HOME/.npm-packages" $ mkdir -p "$NPM_PACKAGES" -
Set NPM to use this directory for its global package installs:
$ echo "prefix = $NPM_PACKAGES" >> ~/.npmrc -
Configure your PATH and MANPATH to see commands in your $NPM_PACKAGES prefix by adding the following to your .bashrc:
```
# NPM packages in homedir
NPM_PACKAGES="$HOME/.npm-packages"Tell our environment about user-ins…
Events triggered by jQuery cannot be observed by native event listeners
jQuery has a function $.fn.trigger(). You can use it to dispatch an event on a jQuery object:
let $element = $('.foo')
$element.trigger('change')
A caveat is that such an event will be received by jQuery event listeners, but not by native event listeners:
let $element = $('.foo')
$element.on('change', event => console.log('I will be called'))
$element[0].addEventListener('change', event => console.log('I WON'T be called'))
$element.trigger('change')
This is currently a WONTFIX for jQuery (see c…
Updated: Fixing flaky integration tests
The section "Tool 5: Ensure no other scenarios are bleeding in" was added.
Why two Ruby Time objects are not equal, although they appear to be
So you are comparing two Time objects in an RSpec example, and they are not equal, although they look equal:
expected: Tue May 01 21:59:59 UTC 2007,
got: Tue May 01 21:59:59 UTC 2007 (using ==)
The reason for this is that Time actually tracks fractions of a second, although #to_s doesn't say so and even though you probably only care about seconds. This means that two consecutive calls of Time.now probably return two inequal values.
Consider freezing time in your tests so it is not dependent on the speed of the executi…