Sync with upstream @ 08734734

1-js/01-getting-started/1-intro/article.md

@@ -6,7 +6,11 @@ Vamos ver o que há de tão especial no JavaScript, o que podemos fazer com ele,
 
 *JavaScript* foi inicialmente criado para *" tornar páginas web vivas "*.
 
+<<<<<<< HEAD
 Os programas nesta linguagem são chamados de *scripts*. Eles podem ser escritos diretamente no HTML de uma página web e executados automaticamente quando a página é carregada.
+=======
+The programs in this language are called *scripts*. They can be written right in a web page's HTML and run automatically as the page loads.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 Os scripts são fornecidos e executados como texto puro. Eles não precisam de preparação ou compilação especial para serem executados.
 
@@ -70,7 +74,11 @@ Exemplos de tais restrições incluem:
    Existem maneiras de interagir com a câmera / microfone e outros dispositivos, mas eles exigem permissão explícita do usuário. Assim, uma página habilitada para JavaScript pode não habilmente habilitar uma câmera web, observar os arredores e enviar as informações para a [NSA](https://pt.wikipedia.org/wiki/Ag%C3%AAncia_de_Seguran%C3%A7a_Nacional).
 - Diferentes abas/janelas geralmente não se conhecem mutuamente. Às vezes sim, por exemplo, quando uma janela usa JavaScript para abrir a outra. Mas mesmo neste caso, JavaScript de uma página pode não acessar a outra se eles vierem de sites diferentes (de um domínio, protocolo ou porta diferente).
 
+<<<<<<< HEAD
     Isso é chamado de "Política de mesma origem ". Para contornar isso, *ambas as páginas* devem conter um código JavaScript especial que lida com a troca de dados.
+=======
+    This is called the "Same Origin Policy". To work around that, *both pages* must agree for data exchange and contain a special JavaScript code that handles it. We'll cover that in the tutorial.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
     Essa limitação é, novamente, para a segurança do usuário. Uma página de `http://umsitequalquer.com.br` que um usuário abriu não deve poder alcançar uma outra aba do navegador com a URL `http://gmail.com` e roubar a informação de lá.
 - O JavaScript pode se comunicar facilmente pela rede com o servidor de onde a página atual veio. Mas sua capacidade de receber dados de outros sites / domínios é prejudicada. Embora possível, requer acordo explícito (expresso em cabeçalhos HTTP) do lado remoto. Mais uma vez, isso é uma limitação de segurança.

1-js/02-first-steps/01-hello-world/article.md

@@ -1,6 +1,10 @@
 # Olá, mundo!
 
+<<<<<<< HEAD
 O tutorial que você está lendo é sobre a core do JavaScript, que é independente de plataforma. Mais tarde, você vai aprender sobre Node.js e outras plataformas que o usam.
+=======
+This part of the tutorial is about core JavaScript, the language itself. Later on, you'll learn about Node.js and other platforms that use it.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 Mas precisamos de um ambiente de trabalho para rodar nossos scripts e, como esse livro está online, o navegador é uma boa escolha. Vamos manter a quantidade de comandos específicos do navegador (como `alert`) no mínimo para que você não gaste tempo com eles se você planeja se concentrar em outro ambiente (como Node.js). Vamos focar em JavaScript no navegador na [próxima parte](/ui) do tutorial.
 
@@ -45,8 +49,13 @@ A tag `<script>` contém código JavaScript que é executado automaticamente qua
 
 A tag `<script>` tem alguns atributos que raramente são usados hoje em dia, mas que ainda podem ser encontrados em códigos antigos:
 
+<<<<<<< HEAD
 O atributo `type`: <code>&lt;script <u>type</u>=...&gt;</code>
 : O antigo padrão HTML, HTML4, requeria um script para ter um `type`. Normalmente era `type="text/javascript"`. Não é mais necessário. Além disso, o moderno padrão HTML, HTML5, mudou totalmente o significado deste atributo. Agora, ele pode ser usado para módulos JavaScript. Mas esse é um tópico avançado; vamos falar sobre módulos em outra parte do tutorial. 
+=======
+The `type` attribute: <code>&lt;script <u>type</u>=...&gt;</code>
+: The old HTML standard, HTML4, required a script to have a `type`. Usually it was `type="text/javascript"`. It's not required anymore. Also, the modern HTML standard, HTML5, totally changed the meaning of this attribute. Now, it can be used for JavaScript modules. But that's an advanced topic; we'll talk about modules in another part of the tutorial.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 O atributo `language`: <code>&lt;script <u>language</u>=...&gt;</code>
 : Este atributo foi criado para mostrar o idioma do script. Este atributo não faz mais sentido porque JavaScript é a linguagem padrão. Não há necessidade de usá-lo.

1-js/02-first-steps/04-variables/article.md

@@ -135,8 +135,13 @@ alert(hello); // Olá Mundo!
 alert(message); // Olá Mundo!
 ```
 
+<<<<<<< HEAD
 ```smart header="Linguagens funcionais"
 É interessante notar que linguagens de programação [funcional](https://en.wikipedia.org/wiki/Functional_programming), como [Scala](http://www.scala-lang.org/) or [Erlang](http://www.erlang.org/), proibem a modificação de valores de variáveis.
+=======
+```smart header="Functional languages"
+It's interesting to note that there exist [functional](https://en.wikipedia.org/wiki/Functional_programming) programming languages, like [Scala](http://www.scala-lang.org/) or [Erlang](http://www.erlang.org/) that forbid changing variable values.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 Em tais linguagens, uma vez que o valor é armazenado "na box", ele está lá para sempre. Se precisarmos de armazenar algo mais, a linguagem nos obriga a criar uma nova box (declarar uma nova variável). Não podemos reutilizar a antiga.
 
@@ -182,8 +187,13 @@ let my-name; // hífens '-' não são permitidos no nome
 Variáveis chamadas `apple` e `AppLE` são duas variáveis diferentes.
 ```
 
+<<<<<<< HEAD
 ````smart header="Letras não inglesas são permitidas, mas não são recomendadas"
 É possível usar qualquer idioma, incluindo letras cirílicas ou até hieróglifos, como este:
+=======
+````smart header="Non-Latin letters are allowed, but not recommended"
+It is possible to use any language, including cyrillic letters or even hieroglyphs, like this:
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 ```js
 let имя = '...';
@@ -254,7 +264,11 @@ Há uma prática generalizada de usar constantes como aliases para valores difí
 
 Tais constantes são nomeadas usando letras maiúsculas e sublinhados.
 
+<<<<<<< HEAD
 Como estas:
+=======
+For instance, let's make constants for colors in so-called "web" (hexadecimal) format:
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 ```js run
 const COLOR_RED = "#F00";
@@ -290,7 +304,11 @@ Em outras palavras, constantes com nomes maiúsculos são usadas apenas como pse
 
 Falando em variáveis, há mais uma coisa extremamente importante.
 
+<<<<<<< HEAD
 Por favor, nomeie as suas variáveis de forma sensata. Tome tempo para pensar sobre isso.
+=======
+A variable name should have a clean, obvious meaning, describe the data that it stores.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 A nomenclatura variável é uma das habilidades mais importantes e complexas em programação. Uma rápida olhada em nomes de variáveis pode revelar qual código foi escrito por um iniciante versus um desenvolvedor experiente.
 

1-js/02-first-steps/05-types/article.md

@@ -226,7 +226,11 @@ As três últimas linhas podem precisar de explicações adicionais:
 
 ## Resumo
 
+<<<<<<< HEAD
 Existem 7 tipos básicos em JavaScript.
+=======
+There are 7 basic data types in JavaScript.
+>>>>>>> 08734734021aa128c13da2382fe8fa062677bb9f
 
 - `number` para números de qualquer tipo: inteiro ou ponto flutuante.
 - `string` para cordas. Uma cadeia de caracteres pode ter um ou mais caracteres, não há nenhum tipo de caractere único separado.

1-js/02-first-steps/08-comparison/article.md

@@ -193,7 +193,7 @@ Why does it dislike zero so much? Always false!
 We get these results because:
 
 - Comparisons `(1)` and `(2)` return `false` because `undefined` gets converted to `NaN` and `NaN` is a special numeric value which returns `false` for all comparisons.
-- The equality check `(3)` returns `false` because `undefined` only equals `null` and no other value.
+- The equality check `(3)` returns `false` because `undefined` only equals `null`, `undefined`, and no other value.
 
 ### Evade problems
 

1-js/02-first-steps/09-alert-prompt-confirm/article.md

@@ -1,6 +1,6 @@
 # Interaction: alert, prompt, confirm
 
-This part of the tutorial aims to cover JavaScript "as is", without environment-specific tweaks.
+In this part of the tutorial we cover JavaScript language "as is", without environment-specific tweaks.
 
 But we'll still be using the browser as our demo environment, so we should know at least a few of its user-interface functions. In this chapter, we'll get familiar with the browser functions `alert`, `prompt` and `confirm`.
 

1-js/02-first-steps/10-ifelse/article.md

@@ -2,7 +2,7 @@
 
 Sometimes, we need to perform different actions based on different conditions.
 
-To do that, we use the `if` statement and the conditional (ternary) operator which we will be referring to as the “question mark” operator `?` for simplicity.
+To do that, we can use the `if` statement and the conditional operator `?`, that's also called a "question mark" operator.
 
 ## The "if" statement
 
@@ -103,7 +103,7 @@ In the code above, JavaScript first checks `year < 2015`. If that is falsy, it g
 
 There can be more `else if` blocks. The final `else` is optional.
 
-## Ternary operator '?'
+## Conditional operator '?'
 
 Sometimes, we need to assign a variable depending on a condition.
 
@@ -124,9 +124,9 @@ if (age > 18) {
 alert(accessAllowed);
 ```
 
-The so-called "ternary" or "question mark" operator lets us do that in a shorter and simpler way.
+The so-called "conditional" or "question mark" operator lets us do that in a shorter and simpler way.
 
-The operator is represented by a question mark `?`.  The formal term "ternary" means that the operator has three operands. It is actually the one and only operator in JavaScript which has that many.
+The operator is represented by a question mark `?`. Sometimes it's called "ternary", because the operator has three operands. It is actually the one and only operator in JavaScript which has that many.
 
 The syntax is:
 ```js
@@ -141,7 +141,7 @@ For example:
 let accessAllowed = (age > 18) ? true : false;
 ```
 
-Technically, we can omit the parentheses around `age > 18`. The question mark operator has a low precedence, so it executes after the comparison `>`. 
+Technically, we can omit the parentheses around `age > 18`. The question mark operator has a low precedence, so it executes after the comparison `>`.
 
 This example will do the same thing as the previous one:
 

1-js/02-first-steps/11-logical-operators/article.md

@@ -84,7 +84,7 @@ The OR `||` operator does the following:
 
 A value is returned in its original form, without the conversion.
 
-In other words, a chain of OR `"||"` returns the first truthy value or the last one if no such value is found.
+In other words, a chain of OR `"||"` returns the first truthy value or the last one if no truthy value is found.
 
 For instance:
 
@@ -101,7 +101,7 @@ This leads to some interesting usage compared to a "pure, classical, boolean-onl
 
 1. **Getting the first truthy value from a list of variables or expressions.**
 
-    Imagine we have several variables which can either contain data or be `null/undefined`. How can we find the first one with data?
+    Imagine we have a list of variables which can either contain data or be `null/undefined`. How can we find the first one with data?
 
     We can use OR `||`:
 
@@ -143,7 +143,7 @@ This leads to some interesting usage compared to a "pure, classical, boolean-onl
     alert(x); // 1
     ```
 
-    An assignment is a simple case. Other side effects can also be involved.
+    An assignment is a simple case. There may be side effects, that won't show up if the evaluation doesn't reach them.
 
     As we can see, such a use case is a "shorter way of doing `if`". The first operand is converted to boolean. If it's false, the second one is evaluated.
 

1-js/02-first-steps/12-while-for/article.md

@@ -47,8 +47,8 @@ while (i) { // when i becomes 0, the condition becomes falsy, and the loop stops
 }
 ```
 
-````smart header="Brackets are not required for a single-line body"
-If the loop body has a single statement, we can omit the brackets `{…}`:
+````smart header="Curly braces are not required for a single-line body"
+If the loop body has a single statement, we can omit the curly braces `{…}`:
 
 ```js run
 let i = 3;

1-js/02-first-steps/14-function-basics/article.md

@@ -101,7 +101,7 @@ showMessage();
 alert( userName ); // *!*Bob*/!*, the value was modified by the function
 ```
 
-The outer variable is only used if there's no local one. So an occasional modification may happen if we forget `let`.
+The outer variable is only used if there's no local one.
 
 If a same-named variable is declared inside the function then it *shadows* the outer one. For instance, in the code below the function uses the local `userName`. The outer one is ignored:
 
@@ -128,7 +128,7 @@ Variables declared outside of any function, such as the outer `userName` in the
 
 Global variables are visible from any function (unless shadowed by locals).
 
-Usually, a function declares all variables specific to its task. Global variables only store project-level data, and it's important that these variables are accessible from anywhere. Modern code has few or no globals. Most variables reside in their functions.
+It's a good practice to minimize the use of global variables. Modern code has few or no globals. Most variables reside in their functions. Sometimes though, they can be useful to store project-level data.
 ```
 
 ## Parameters
@@ -376,7 +376,7 @@ A few examples of breaking this rule:
 - `createForm` -- would be bad if it modifies the document, adding a form to it (should only create it and return).
 - `checkPermission` -- would be bad if it displays the `access granted/denied` message (should only perform the check and return the result).
 
-These examples assume common meanings of prefixes. What they mean for you is determined by you and your team. Maybe it's pretty normal for your code to behave differently. But you should have a firm understanding of what a prefix means, what a prefixed function can and cannot do. All same-prefixed functions should obey the rules. And the team should share the knowledge.
+These examples assume common meanings of prefixes. You and your team are free to agree on other meanings, but usually they're not much different. In any case, you should have a firm understanding of what a prefix means, what a prefixed function can and cannot do. All same-prefixed functions should obey the rules. And the team should share the knowledge.
 ```
 
 ```smart header="Ultrashort function names"

1-js/02-first-steps/15-function-expressions-arrows/article.md

@@ -175,7 +175,7 @@ We can pass it between variables and run when we want.
 
 Let's formulate the key differences between Function Declarations and Expressions.
 
-First, the syntax: how to see what is what in the code.
+First, the syntax: how to differentiate between them in the code.
 
 - *Function Declaration:* a function, declared as a separate statement, in the main code flow.
 
@@ -186,7 +186,7 @@ First, the syntax: how to see what is what in the code.
     }
     ```
 - *Function Expression:* a function, created inside an expression or inside another syntax construct. Here, the function is created at the right side of the "assignment expression" `=`:
-    
+
     ```js
     // Function Expression
     let sum = function(a, b) {
@@ -202,7 +202,7 @@ Once the execution flow passes to the right side of the assignment `let sum = fu
 
 Function Declarations are different.
 
-**A Function Declaration is usable in the whole script/code block.**
+**A Function Declaration is usable in the whole script (or a code block, if it's inside a block).**
 
 In other words, when JavaScript *prepares* to run the script or a code block, it first looks for Function Declarations in it and creates the functions. We can think of it as an "initialization stage".
 

1-js/02-first-steps/16-javascript-specials/article.md

@@ -103,7 +103,7 @@ More in: <info:variables> and <info:types>.
 We're using a browser as a working environment, so basic UI functions will be:
 
 [`prompt(question, [default])`](mdn:api/Window/prompt)
-: Ask a `question`, and return either what the visitor entered or `null` if they pressed "cancel".
+: Ask a `question`, and return either what the visitor entered or `null` if they clicked "cancel".
 
 [`confirm(question)`](mdn:api/Window/confirm)
 : Ask a `question` and suggest to choose between Ok and Cancel. The choice is returned as `true/false`.
@@ -161,7 +161,7 @@ Comparisons
 
     Other comparisons convert to a number as well.
 
-    The strict equality operator `===` doesn't do the conversion: different types always mean different values for it, so:
+    The strict equality operator `===` doesn't do the conversion: different types always mean different values for it.
 
     Values `null` and `undefined` are special: they equal `==` each other and don't equal anything else.
 

1-js/03-code-quality/01-debugging-chrome/article.md

@@ -20,7 +20,7 @@ Here's what you should see if you are doing it for the first time:
 
 The toggler button <span class="devtools" style="background-position:-168px -76px"></span> opens the tab with files.
 
-Let's click it and select `index.html` and then `hello.js` in the tree view. Here's what should show up:
+Let's click it and select `hello.js` in the tree view. Here's what should show up:
 
 ![](chrome-tabs.png)
 
@@ -34,7 +34,7 @@ Now you could click the same toggler <span class="devtools" style="background-po
 
 ## Console
 
-If we press `Esc`, then a console opens below. We can type commands there and press `key:Enter` to execute.
+If we press `key:Esc`, then a console opens below. We can type commands there and press `key:Enter` to execute.
 
 After a statement is executed, its result is shown below.