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@ -26,17 +26,16 @@
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//
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//
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// Imagine an apple, it's a "thing" that is an "apple", or we say that
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// Imagine an apple, it's a "thing" that is an "apple", or we say that
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// it has a value "apple". There are lots of apples in the world,
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// it has a value "apple". There are lots of apples in the world,
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// each one is slightly different but all are apples. Now imagine two
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// each one is different but all are apples. Now imagine two people,
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// people, each looking at an apple, we can say that each person sees
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// each looking at an apple, we can say that each person sees the value
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// the value "apple", those values are equal, and if those people are
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// "apple", those values are equal, and if those people are sitting at
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// sitting at the same table and looking at the same apple, we say that
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// the same table and looking at the same apple, we say that their
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// their apples are the same apple, or in JavaScript-ish, they are of
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// apples are the same, or they are of the same identity, (i.e. the
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// the same identity.
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// same apple).
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// Then if we can take a different set of people looking at apples, but
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// Then if we can take a different set of people looking at apples, but
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// now each one has their own personal apple, the values are still the
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// now each one has their own personal apple, the values are still the
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// same, both apples are still looking at apples but now their apples
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// same, both apples are still apples but now they are different apples,
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// are different, aren't they? And thus we say they are of different
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// aren't they? And thus we say they are of different identities.
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// identities.
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// We'll come back to this concept a bit later, once we introduce
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// We'll come back to this concept a bit later, once we introduce
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// JavaScript values and types.
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// JavaScript values and types.
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//
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//
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@ -50,7 +49,7 @@
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//
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//
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// Note that all numbers are of the same "type", this is different to
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// Note that all numbers are of the same "type", this is different to
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// allot of other languages where numbers are implemented closer to the
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// allot of other languages where numbers are represented closer to the
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// low-level hardware implementation and thus are represented by a
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// low-level hardware implementation and thus are represented by a
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// whole range of number types.
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// whole range of number types.
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//
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//
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@ -59,35 +58,12 @@
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var oct = 052
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var oct = 052
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var hex = 0xFF
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var hex = 0xFF
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var dec = 42
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var dec = 42
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var exp = .42e2
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//
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//
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// But note that these are just different notations and all of the
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// But note that these are just different notations and all of the
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// above resolve to the same number.
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// above resolve to the same number.
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//
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//
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// Numbers also have several limitations:
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//
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// - precision, rounding errors and fractions (IEEE-754)
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0.1 + 0.2 == 0.3 // -> false
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// XXX
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// - large number rounding
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Number.MAX_SAFE_INTEGER + 10 - 10 == Number.MAX_SAFE_INTEGER
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// In general numbers larger than Number.MAX_SAFE_INTEGER and
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// smaller than Number.MIN_SAFE_INTEGER should not be used for
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// math operations (see BigInt).
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//
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// Note that neither issue is specific to JavaScript but rather are
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// side-effects of number implementations in modern computers and
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// the trade-offs of these implementation on each level from the
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// CPU to the high-level languages.
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//
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// For more details see:
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// XXX
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// Strings
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// Strings
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var string = 'string'
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var string = 'string'
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@ -99,12 +75,10 @@
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// XXX a note on template strings
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// XXX a note on template strings
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// Boolieans
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// Booleans
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var t = true
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var t = true
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var f = false
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var f = false
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// Nulls
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// Nulls
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var n = null
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var n = null
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var u = undefined
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var u = undefined
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