Update 02-first-steps/10-ifelse

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

@@ -1,12 +1,12 @@
 # Conditional operators: if, '?'
 
-Sometimes we need to perform different actions based on a condition.
+Sometimes, we need to perform different actions based on different conditions.
 
-There is the `if` statement for that and also the conditional (ternary) operator for conditional evaluation which we will be referring as  the “question mark” operator `?` for simplicity.
+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.
 
 ## The "if" statement
 
-The `if` statement gets a condition, evaluates it and, if the result is `true`, executes the code.
+The `if` statement evaluates a condition and, if the condition's result is `true`, executes a block of code.
 
 For example:
 
@@ -18,9 +18,9 @@ if (year == 2015) alert( 'You are right!' );
 */!*
 ```
 
-In the example above, the condition is a simple equality check: `year == 2015`, but it can be much more complex.
+In the example above, the condition is a simple equality check (`year == 2015`), but it can be much more complex.
 
-If there is more than one statement to be executed, we have to wrap our code block inside curly braces:
+If we want to execute more than one statement, we have to wrap our code block inside curly braces:
 
 ```js
 if (year == 2015) {
@@ -29,15 +29,15 @@ if (year == 2015) {
 }
 ```
 
-It is recommended to wrap your code block with curly braces `{}` every time with `if`, even if there is only one statement. That improves readability.
+We recommend wrapping your code block with curly braces `{}` every time you use an `if` statement, even if there is only one statement to execute. Doing so improves readability.
 
 ## Boolean conversion
 
-The `if (…)` statement evaluates the expression in parentheses and converts it to the boolean type.
+The `if (…)` statement evaluates the expression in its parentheses and converts the result to a boolean.
 
 Let's recall the conversion rules from the chapter <info:type-conversions>:
 
-- A number `0`, an empty string `""`, `null`, `undefined` and `NaN` become `false`. Because of that they are called "falsy" values.
+- A number `0`, an empty string `""`, `null`, `undefined`, and `NaN` all become `false`. Because of that they are called "falsy" values.
 - Other values become `true`, so they are called "truthy".
 
 So, the code under this condition would never execute:
@@ -48,7 +48,7 @@ if (0) { // 0 is falsy
 }
 ```
 
-...And inside this condition -- always works:
+...and inside this condition -- it always will:
 
 ```js
 if (1) { // 1 is truthy
@@ -56,7 +56,7 @@ if (1) { // 1 is truthy
 }
 ```
 
-We can also pass a pre-evaluated boolean value to `if`, like here:
+We can also pass a pre-evaluated boolean value to `if`, like this:
 
 ```js
 let cond = (year == 2015); // equality evaluates to true or false
@@ -68,11 +68,11 @@ if (cond) {
 
 ## The "else" clause
 
-The `if` statement may contain an optional "else" block. It executes when the condition is wrong.
+The `if` statement may contain an optional "else" block. It executes when the condition is false.
 
 For example:
 ```js run
-let year = prompt('In which year was ECMAScript-2015 specification published?', '');
+let year = prompt('In which year was the ECMAScript-2015 specification published?', '');
 
 if (year == 2015) {
   alert( 'You guessed it right!' );
@@ -83,12 +83,12 @@ if (year == 2015) {
 
 ## Several conditions: "else if"
 
-Sometimes we'd like to test several variants of a condition. There is an `else if` clause for that.
+Sometimes, we'd like to test several variants of a condition. The `else if` clause lets us do that.
 
 For example:
 
 ```js run
-let year = prompt('In which year was ECMAScript-2015 specification published?', '');
+let year = prompt('In which year was the ECMAScript-2015 specification published?', '');
 
 if (year < 2015) {
   alert( 'Too early...' );
@@ -99,13 +99,13 @@ if (year < 2015) {
 }
 ```
 
-In the code above JavaScript first checks `year < 2015`. If it is falsy it then goes to the next condition `year > 2015`, and otherwise shows the last `alert`.
+In the code above, JavaScript first checks `year < 2015`. If that is falsy, it goes to the next condition `year > 2015`. If that is also falsy, it shows the last `alert`.
 
-There can be more `else if` blocks. The ending `else` is optional.
+There can be more `else if` blocks. The final `else` is optional.
 
 ## Ternary operator '?'
 
-Sometimes we need to assign a variable depending on a condition.
+Sometimes, we need to assign a variable depending on a condition.
 
 For instance:
 
@@ -124,16 +124,16 @@ if (age > 18) {
 alert(accessAllowed);
 ```
 
-The so-called "ternary" or "question mark" operator lets us do that shorter and simpler.
+The so-called "ternary" 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 syntax is:
 ```js
-let result = condition ? value1 : value2
+let result = condition ? value1 : value2;
 ```
 
-The `condition` is evaluated, if it's truthy then `value1` is returned, otherwise -- `value2`.
+The `condition` is evaluated: if it's truthy then `value1` is returned, otherwise -- `value2`.
 
 For example:
 
@@ -141,7 +141,9 @@ For example:
 let accessAllowed = (age > 18) ? true : false;
 ```
 
-Technically, we can omit parentheses around `age > 18`. The question mark operator has a low precedence. It executes after the comparison `>`, so that'll do the same:
+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:
 
 ```js
 // the comparison operator "age > 18" executes first anyway
@@ -149,10 +151,10 @@ Technically, we can omit parentheses around `age > 18`. The question mark operat
 let accessAllowed = age > 18 ? true : false;
 ```
 
-But parentheses make the code more readable, so it's recommended to use them.
+But parentheses make the code more readable, so we recommend using them.
 
 ````smart
-In the example above it's possible to evade the question mark operator, because the comparison by itself returns `true/false`:
+In the example above, you can avoid using the question mark operator because the comparison itself returns `true/false`:
 
 ```js
 // the same
@@ -162,7 +164,7 @@ let accessAllowed = age > 18;
 
 ## Multiple '?'
 
-A sequence of question mark `?` operators allows returning a value that depends on more than one condition.
+A sequence of question mark operators `?` can return a value that depends on more than one condition.
 
 For instance:
 ```js run
@@ -176,14 +178,14 @@ let message = (age < 3) ? 'Hi, baby!' :
 alert( message );
 ```
 
-It may be difficult at first to grasp what's going on. But after a closer look we can see that it's just an ordinary sequence of tests.
+It may be difficult at first to grasp what's going on. But after a closer look, we can see that it's just an ordinary sequence of tests:
 
 1. The first question mark checks whether `age < 3`.
-2. If true -- returns `'Hi, baby!'`, otherwise -- goes after the colon `":"` and checks for `age < 18`.
-3. If that's true -- returns `'Hello!'`, otherwise -- goes after the next colon `":"` and checks for `age < 100`.
-4. If that's true -- returns `'Greetings!'`, otherwise -- goes after the last colon `":"` and returns `'What an unusual age!'`.
+2. If true -- it returns `'Hi, baby!'`. Otherwise, it continues to the expression after the colon '":"', checking `age < 18`.
+3. If that's true -- it returns `'Hello!'`. Otherwise, it continues to the expression after the next colon '":"', checking `age < 100`.
+4. If that's true -- it returns `'Greetings!'`. Otherwise, it continues to the expression after the last colon '":"', returning `'What an unusual age!'`.
 
-The same logic using `if..else`:
+Here's how this looks using `if..else`:
 
 ```js
 if (age < 3) {
@@ -210,15 +212,15 @@ let company = prompt('Which company created JavaScript?', '');
 */!*
 ```
 
-Depending on the condition `company == 'Netscape'`, either the first or the second part after `?` gets executed and shows the alert.
+Depending on the condition `company == 'Netscape'`, either the first or the second expression after the `?` gets executed and shows an alert.
 
-We don't assign a result to a variable here. The idea is to execute different code depending on the condition.
+We don't assign a result to a variable here. Instead, we execute different code depending on the condition.
 
-**It is not recommended to use the question mark operator in this way.**
+**We don't recommend using the question mark operator in this way.**
 
-The notation seems to be shorter than `if`, which appeals to some programmers. But it is less readable.
+The notation is shorter than the equivalent `if` statement, which appeals to some programmers. But it is less readable.
 
-Here is the same code with `if` for comparison:
+Here is the same code using `if` for comparison:
 
 ```js run no-beautify
 let company = prompt('Which company created JavaScript?', '');
@@ -232,6 +234,6 @@ if (company == 'Netscape') {
 */!*
 ```
 
-Our eyes scan the code vertically. The constructs which span several lines are easier to understand than a long horizontal instruction set.
+Our eyes scan the code vertically. Code blocks which span several lines are easier to understand than a long, horizontal instruction set.
 
-The idea of a question mark `?` is to return one or another value depending on the condition. Please use it for exactly that. There is `if` to execute different branches of the code.
+The purpose of the question mark operator `?` is to return one value or another depending on its condition. Please use it for exactly that. Use `if` when you need to execute different branches of code.