fangxing fffx

Experimental Safe JavaScript Navigation

Implemented using ES6 Proxies and Symbols

The purpose of this function is to provide a way to avoid deep nested conditionals when traversing a hierarchy of objects. Some languages use an operator such as '?.' to perform this capability. This is sometimes called safe navigation or null conditional operators.

You can somewhat think of this as how a xpath select works. If any nodes along the path are not found, your result is simply not found without throwing an exception and without needing to check each individual node to see if it exists.

Suggestions for improvements welcome!

TracePoint and Rails reload! / startup

On a specific rails application (4.2), when a developper call reload! method on a console he'll see:

Engine Load (0.3ms)  SELECT  `engines`.* FROM `engines` WHERE `engines`.`label` = 'influencer' LIMIT 1
Engine Load (0.3ms)  SELECT  `engines`.* FROM `engines` WHERE `engines`.`label` = 'speaker' LIMIT 1
Engine Load (0.3ms)  SELECT  `engines`.* FROM `engines` WHERE `engines`.`label` = 'animator' LIMIT 1
Engine Load (0.2ms)  SELECT  `engines`.* FROM `engines` WHERE `engines`.`label` = 'ambassador' LIMIT 1
Engine Load (0.2ms) SELECT `engines`.* FROM `engines` WHERE `engines`.`label` = 'private_show' LIMIT 1

We will first discussed how destructing and rest parameters can be used in ES6 - in arrays and objects. Then we will look at a few examples and also discuss some quiz.

arrays

var array = [1, 2, 3, 4];
var nestedArray = [1, 2, 3, 4, [7, 8, 9]];

var [a, b, c, d] = array;
console.log(a, b, c, d)

All Android Directory Path

1) System directories

⚠️ We can't write to these folers

Method	Result

Setting up iOS Universal Links

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

pluck_in_batches

Sometimes you need to iterate over a ton of items and you don't want the overhead of creating AR objects out of all of them. Hell, you only need a few things! Well, #pluck has your back.

But what if you want to iterate over many tonnes of items?

Pluck in batches to the rescue!

Enjoy!

	module ArelHelpers
	extend self

	def self.included(base)
	base.extend self
	end

	def asterisk(arel_table_or_model)
	arel_table, columns = case arel_table_or_model
	when Arel::Table

	#!/usr/local/bin/python
	import os
	import sys
	import csv
	from operator import itemgetter
	from bs4 import BeautifulSoup
	from anki import Collection as aopen


	usmle_rx = open("/Users/drlulz/Desktop/test.html",'r').read()

	// 检测浏览器的 User Agent 应该是非常简单的事情
	// 微信在 Android 下的 User Agent
	mozilla/5.0 (linux; u; android 4.1.2; zh-cn; mi-one plus build/jzo54k) applewebkit/534.30 (khtml, like gecko) version/4.0 mobile safari/534.30 micromessenger/5.0.1.352

	// 微信在 iPhone 下的 User Agent
	mozilla/5.0 (iphone; cpu iphone os 5_1_1 like mac os x) applewebkit/534.46 (khtml, like gecko) mobile/9b206 micromessenger/5.0

	// 通过javascript判断
	// 很容易看出来，微信的 User Agent 都有‘micromessenger’字符串标示，我们判断是否含有这些字符串就OK了
	function isWeixinBrowser(){