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-rw-r--r--javascript.html.markdown27
1 files changed, 17 insertions, 10 deletions
diff --git a/javascript.html.markdown b/javascript.html.markdown
index 7c869b28..aabd5e43 100644
--- a/javascript.html.markdown
+++ b/javascript.html.markdown
@@ -39,13 +39,14 @@ doStuff()
// 1. Numbers, Strings and Operators
// JavaScript has one number type (which is a 64-bit IEEE 754 double).
-// As with Lua, don't freak out about the lack of ints: doubles have a 52-bit
-// mantissa, which is enough to store integers up to about 9✕10¹⁵ precisely.
+// Doubles have a 52-bit mantissa, which is enough to store integers
+// up to about 9✕10¹⁵ precisely.
3; // = 3
1.5; // = 1.5
-// All the basic arithmetic works as you'd expect.
+// Some basic arithmetic works as you'd expect.
1 + 1; // = 2
+0.1 + 0.2; // = 0.30000000000000004
8 - 1; // = 7
10 * 2; // = 20
35 / 5; // = 7
@@ -77,13 +78,13 @@ false;
!true; // = false
!false; // = true
-// Equality is ==
-1 == 1; // = true
-2 == 1; // = false
+// Equality is ===
+1 === 1; // = true
+2 === 1; // = false
-// Inequality is !=
-1 != 1; // = false
-2 != 1; // = true
+// Inequality is !==
+1 !== 1; // = false
+2 !== 1; // = true
// More comparisons
1 < 10; // = true
@@ -97,11 +98,17 @@ false;
// and are compared with < and >
"a" < "b"; // = true
-// Type coercion is performed for comparisons...
+// Type coercion is performed for comparisons with double equals...
"5" == 5; // = true
+null == undefined; // = true
// ...unless you use ===
"5" === 5; // = false
+null === undefined; // = false
+
+// ...which can result in some weird behaviour...
+13 + !0; // 14
+"13" + !0; // '13true'
// You can access characters in a string with charAt
"This is a string".charAt(0); // = 'T'