summaryrefslogtreecommitdiffhomepage
path: root/javascript.html.markdown
diff options
context:
space:
mode:
Diffstat (limited to 'javascript.html.markdown')
-rw-r--r--javascript.html.markdown17
1 files changed, 6 insertions, 11 deletions
diff --git a/javascript.html.markdown b/javascript.html.markdown
index bcaf9a29..9b87b022 100644
--- a/javascript.html.markdown
+++ b/javascript.html.markdown
@@ -185,7 +185,7 @@ do {
input = getInput()
} while (!isValid(input))
-// the for loop is the same as C and Java:
+// the for loop is the same as C and Java:
// initialisation; continue condition; iteration.
for (var i = 0; i < 5; i++){
// will run 5 times
@@ -255,24 +255,19 @@ permanent // = 10
// One of JavaScript's most powerful features is closures. If a function is
// defined inside another function, the inner function has access to all the
-// outer function's variables.
+// outer function's variables, even after the outer function exits.
function sayHelloInFiveSeconds(name){
var prompt = "Hello, " + name + "!"
function inner(){
alert(prompt)
}
setTimeout(inner, 5000)
- // setTimeout is asynchronous, so this function will finish without waiting
- // 5 seconds. However, once the 5 seconds is up, inner will still have
- // access to the value of prompt.
+ // setTimeout is asynchronous, so the sayHelloInFiveSeconds function will
+ // exit immediately, and setTimeout will call inner afterwards. However,
+ // because inner is "closed over" sayHelloInFiveSeconds, inner still has
+ // access to the 'prompt' variable when it is finally called.
}
sayHelloInFiveSeconds("Adam") // will open a popup with "Hello, Adam!" in 5s
-// inner() has access to the variable "prompt" strictly because of lexical scope.
-// A closure is being demonstrated because the inner() function is being executed
-// at a later time, and in fact being executed "outside" the scope where it was
-// declared (inside of the implementation of setTimeout()), but yet inner() STILL
-// has access to the variable "prompt". It is said that inner() has a "closure"
-// over the variables of sayHelloInFiveSeconds().
///////////////////////////////////
// 5. More about Objects; Constructors and Prototypes