Conditionals
forks in the road
Tuesday, September 22, 2009
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Tuesday, September 22, 2009
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Tuesday, September 22, 2009
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Tuesday, September 22, 2009
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if statement
execute some code only if a statement is true
http://www.w3schools.com/JS/js_if_else.asp
Tuesday, September 22, 2009
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if
Tuesday, September 22, 2009
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if (conditional)
Tuesday, September 22, 2009
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if (conditional) {
Tuesday, September 22, 2009
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if (conditional) {
// statement to be executed
Tuesday, September 22, 2009
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if (conditional) {
// statement to be executed
}
Tuesday, September 22, 2009
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true
false
Tuesday, September 22, 2009
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var age = 60;
var status = null;
if (age > 62) {
status = 'retired';
}
status; // null
Tuesday, September 22, 2009
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var age = 60;
var status = null;
if (age > 62) {
status = 'retired';
}
status; // null
60 > 62 === false
this never executes
so status is never assigned
and remains null
Tuesday, September 22, 2009
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var age = 65;
var status = null;
if (age > 62) {
status = 'retired';
}
status; // "retired"
Tuesday, September 22, 2009
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var age = 65;
var status = null;
if (age > 62) {
status = 'retired';
}
status; // "retired"
65 > 62 === true
this executes
so status is set to “retired”
Tuesday, September 22, 2009
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if...else statement
execute some code if statement is true
and some other code if statement is false
http://www.w3schools.com/JS/js_if_else.asp
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
}
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
} else
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
} else {
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
} else {
// statement if false
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
} else {
// statement if false
}
Tuesday, September 22, 2009
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true
false
Tuesday, September 22, 2009
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var age = 60;
var status = null;
if (age > 62) {
status = 'retired';
} else {
status = 'not retired';
}
status; // "not retired"
Tuesday, September 22, 2009
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var age = 65;
var status = null;
if (age > 62) {
status = 'retired';
} else {
status = 'not retired';
}
status; // "retired"
Tuesday, September 22, 2009
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if...else if...else statement
execute some code if statement is true
and some other code if statement is false
http://www.w3schools.com/JS/js_if_else.asp
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
} else if (conditional) {
// statement if false and else if true
} else {
// statement if all false
}
Tuesday, September 22, 2009
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if (conditional) {
// statement if true
} else if (conditional) {
// whichever matches first
} else if (conditional) {
// whichever matches first
} else if (conditional) {
// whichever matches first
} else {
// statement if all false
}
Tuesday, September 22, 2009
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var age = 19;
var status = null;
if (age >= 62) {
status = 'retired';
} else if (age > 22 && age < 62) {
status = 'working';
} else if (age >= 18 && age <= 22) {
status = 'college';
} else {
status = 'no responsibilities';
}
status;
Tuesday, September 22, 2009
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switch statement
select one of many blocks of code to execute
http://www.w3schools.com/JS/js_switch.asp
Tuesday, September 22, 2009
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switch
Tuesday, September 22, 2009
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switch (value)
Tuesday, September 22, 2009
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switch (value) {
Tuesday, September 22, 2009
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switch (value) {
case 1:
Tuesday, September 22, 2009
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switch (value) {
case 1:
// some code to execute
Tuesday, September 22, 2009
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switch (value) {
case 1:
// some code to execute
break;
Tuesday, September 22, 2009
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switch (value) {
case 1:
// some code to execute
break;
case 2:
// some code to execute
break;
Tuesday, September 22, 2009
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switch (value) {
case 1:
// some code to execute
break;
case 2:
// some code to execute
break;
default:
// nothing matched so do this
Tuesday, September 22, 2009
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switch (value) {
case 1:
// some code to execute
break;
case 2:
// some code to execute
break;
default:
// nothing matched so do this
similar to else in if...else
Tuesday, September 22, 2009
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switch (value) {
case 1:
// some code to execute
break;
case 2:
// some code to execute
break;
default:
// nothing matched so do this
}
Tuesday, September 22, 2009
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var age = 18;
switch (typeof(age)) {
case 'number':
"I'm a number!";
break;
case 'string':
"I'm a string!";
break;
case 'boolean':
"I'm a boolean!";
break;
default:
"I don't know what I am!";
}
// "I'm a number!"
Tuesday, September 22, 2009
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for(action in json) {
var selectors = json[action];
switch(action) {
case 'replace' : for(selector in selectors) $(selector).html(selectors[selector]); break;
case 'append' : for(selector in selectors) $(selector).append(selectors[selector]); break;
case 'prepend' : for(selector in selectors) $(selector).prepend(selectors[selector]); break;
case 'replaceWith' : for(selector in selectors) $(selector).replaceWith(selectors[selector]); break;
case 'insertBefore' : for(selector in selectors) $(selectors[selector]).insertBefore($(selector)); break;
case 'sidebar' : Sidebar.add(selectors); break;
case 'remove' : $(selectors.join(',')).remove(); break;
}
}
Tuesday, September 22, 2009
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Review
Tuesday, September 22, 2009
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var age = 18;
var teens = false;
if (age > 12 && age < 20) {
teens = true;
}
teens;
Tuesday, September 22, 2009
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var age = 18;
var teens = false;
if (age > 12 && age < 20) {
teens = true;
}
teens; // true
Tuesday, September 22, 2009
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var days = ['sunday', 'monday', 'tuesday'];
var first = days[0];
var week_starts_on_sunday = false;
if (first === 'sunday') {
week_starts_on_sunday = true;
}
week_starts_on_sunday;
Tuesday, September 22, 2009
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var days = ['sunday', 'monday', 'tuesday'];
var first = days[0];
var week_starts_on_sunday = false;
if (first === 'sunday') {
week_starts_on_sunday = true;
}
week_starts_on_sunday; // true
Tuesday, September 22, 2009
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var days = ['monday', 'tuesday', 'sunday'];
var first = days[0];
var week_starts_on_sunday = false;
if (first === 'sunday') {
week_starts_on_sunday = true;
}
week_starts_on_sunday;
Tuesday, September 22, 2009
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var days = ['monday', 'tuesday', 'sunday'];
var first = days[0];
var week_starts_on_sunday = false;
if (first === 'sunday') {
week_starts_on_sunday = true;
}
week_starts_on_sunday; // false
Tuesday, September 22, 2009
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Assignment
http://teaching.johnnunemaker.com/capp-30550/sessions/conditionals
Tuesday, September 22, 2009