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Learn JavaScript concepts with the Chrome DevTools

Authored by Peter Rybin , Chrome DevTools team

In this short guide we'll review some new Chrome DevTools features for "function scope" and "internal properties" by exploring some base JavaScript language concepts.

Closures

Let's start with closures – one of the most famous things in JS. A closure is a function, that uses variables from outside. See an example:

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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.

Element

Box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
• elem.clientLeft, elem.clientTop, elem.clientWidth, elem.clientHeight
• elem.getClientRects(), elem.getBoundingClientRect()

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Memory management

Each process have its own stack and heap, while threads share common heap.

• Elements of a process
• Memory Allocation/Deallocation Bottleneck?
• Do different programs gets their memory from a common heap or from a separate heap?

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package main

import "fmt"

func main() {
	fmt.Println(f(5, 3))
}

func f(n, m int) int {
	if n <= 0 || m <= 0 {

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package main

import (
	"fmt"
	"github.com/CenturyLinkLabs/docker-reg-client/registry"
	"net/url"
)

func main() {

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# Mac OS X Lion introduced a new, iOS-like context menu when you press and hold a key
# that enables you to choose a character from a menu of options. If you are on Lion
# try it by pressing and holding down 'e' in any app that uses the default NSTextField
# for input.
#
# It's a nice feature and continues the blending of Mac OS X and iOS features. However,
# it's a nightmare to deal with in Sublime Text if you're running Vintage (Vim) mode,
# as it means you cannot press and hold h/j/k/l to move through your file. You have
# to repeatedly press the keys to navigate.

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package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	var jsonBlob = []byte(`{
    		"repo_info": {

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#!/bin/bash
/bin/sh -c "while true; do echo hello world; sleep 1; done"

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include $(GOROOT)/src/Make.inc

GOFMT=gofmt -spaces=true -tabindent=false -tabwidth=4

all:
	$(GC) jsontest.go 
	$(LD) -o jsontest.out  jsontest.$O

format:
	$(GOFMT) -w jsontest.go

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// URL: http://stackoverflow.com/questions/24864956/angularjs-how-do-i-access-directive-attribute-in-controller

app.directive('rating', [function () {
    return {
        restrict: 'E',
        scope: {
            maxStars: '=',
            url: '@'
        },
        controller: 'ratingController'