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First pass over chapter 5
Different example data, use arrow functions, go into depth on UTF-16.
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‎01_values.md‎

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@@ -288,13 +288,14 @@ character is written like "\n"._” can be expressed:
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"A newline character is written like \"\\n\"."
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```
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{{id unicode}}
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{{index [string, representation], Unicode, character}}
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Strings, too, have to be modeled as a series of bits to be able to
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exist inside the computer. The way JavaScript does this is based on
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the _((Unicode))_ standard. This standard assigns a number to
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virtually every character you would ever need, including characters
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from Greek, Arabic, Japanese, Tamil, and so on. If we have a number
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from Greek, Arabic, Japanese, Armenian, and so on. If we have a number
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for every character, a string can be described by a sequence of
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numbers.
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‎02_program_structure.md‎

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#######
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```
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{{index [string, length]}}
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It may be useful to know that you can find the length of a string by
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writing `.length` after it.
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‎04_data.md‎

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@@ -652,6 +652,8 @@ The only step remaining is to find a correlation for every type of
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event that was recorded and see whether anything stands out. How
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should we store these correlations once we compute them?
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{{id for_of_loop}}
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## Array loops
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{{index "for loop", loop, [array, iteration]}}
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When a `for` loops looks like this, with the word `of` after a
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variable definition, it will loop over the elements of the value given
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after `of`. This works not only for arrays, but also for some other
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data structures. We'll discuss _how_ it works in [Chapter
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after `of`. This works not only for arrays, but also for strings and
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some other data structures. We'll discuss _how_ it works in [Chapter
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6](06_object.html).
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## Objects as maps
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// and so on...
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```
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{{index "for/in loop"}}
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{{index "Object.keys function"}}
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Most correlations seem to lie close to zero. Eating carrots, bread, or
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pudding apparently does not trigger squirrel-lycanthropy. It _does_
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For example, `Math.max` computes the maximum of _all_ the arguments it
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is given.
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{{indexsee "period character", "max example"}}
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{{indexsee "period character", "max example", spread}}
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To write such a function, you put three dots before the function's
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last ((parameter)), like this:
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before it, their values aren't part of that array. But if it's the
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first parameter, as in `max`, it will hold all arguments.
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{{index "function application"}}
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You can use a similar three-dot notation to _call_ a function with an
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array of arguments.
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```
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let numbers = [5, 1, 7];
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console.log(max(...numbers));
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// → 7
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```
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This "((spread))s" out the array into the function call, passing its
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elements as separate arguments. It is possible to include an array
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like that along with other arguments, as in `max(9, ...numbers, 2)`.
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## The Math object
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{{index "Math object", "Math.min function", "Math.max function", "Math.sqrt function", minimum, maximum, "square root"}}
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This also works for ((binding))s created with `let`, `var`, or
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`const`. If you know the value you are binding is an array, you can
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use ((square brackets)) to "look inside" of the value, binding its
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content.
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content. This works well with `Object.entries`, for example.
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```
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let [a, b, c] = [1, 2, 3];
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console.log(b);
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// → 2
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for (let [name, value] in {x: 0, y: 1}) {
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console.log(name, value);
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}
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// → x 0
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// → y 1
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```
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{{index object, "curly braces"}}
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other cases you can just immediately return the result of applying
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`===`.
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{{index "for/in loop", "in operator"}}
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{{index "Object.keys method", "in operator"}}
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Use a `for`/`in` loop to go over the properties. You need to test
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whether both objects have the same set of property names and whether
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those properties have identical values. The first test can be done by
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Use `Object.keys` to go over the properties. You need to test whether
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both objects have the same set of property names and whether those
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properties have identical values. The first test can be done by
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counting the properties in both objects and returning false if the
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numbers of properties are different. If they're the same, then go over
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the properties of one object, and for each of them, verify that the

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