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// 1: how could you rewrite the following to make it shorter? | |
if (foo) { | |
bar.doSomething(el); | |
} else { | |
bar.doSomethingElse(el); | |
} | |
1) (foo?bar.doSomething:bar.doSomethingElse)(el); // <-- minimizers can still work here | |
2) bar[foo?"doSomething":"doSomethingElse"](el); // <-- goodbye method renaming | |
3) bar["doSomething"+(foo?"":"Else")](el); | |
// 2: what is the faulty logic in the following code? | |
var foo = 'hello'; | |
(function() { | |
var foo = foo || 'world'; | |
console.log(foo); | |
})(); | |
/* | |
outer foo will never be accessible when you enter the function since it will be | |
shadowed by the local foo var, console.log will always print "world". | |
*/ | |
// 3: given the following code, how would you override the value of the bar | |
// property for the variable foo without affecting the value of the bar | |
// property for the variable bim? | |
foo.bar = 'baz'; | |
// how would you affect the value of the bar | |
// property for both foo and bim? | |
Thinger.prototype.bar = 'baz'; /* assuming it hasn't been set in the object | |
itself */ | |
// how would you add a method to foo and bim to | |
// console.log the value of each object's bar property? | |
Thinger.prototype.printBar = function() { | |
console.log(this.bar); | |
}; | |
// how would you tell if | |
// the object's bar property had been overridden for the particular object? | |
obj.hasOwnProperty("bar"); | |
var Thinger = function() { | |
return this; | |
}; | |
Thinger.prototype = { | |
bar : 'baz' | |
}; | |
var foo = new Thinger(), | |
bim = new Thinger(); | |
// 4: given the following code, and assuming that each defined object has a | |
// 'destroy' method, how would you destroy all of the objects contained in the | |
// myObjects object? | |
var myObjects = { | |
thinger : new myApp.Thinger(), | |
gizmo : new myApp.Gizmo(), | |
widget : new myApp.Widget() | |
}; | |
for( var object in myObjects ) if( myObjects.hasOwnProperty(object) ) { | |
myObjects[object].destroy(); | |
} | |
// 5: given the following array, create an array that contains the contents of | |
// each array item repeated three times, with a space between each item. so, | |
// for example, if an array item is 'foo' then the new array should contain an | |
// array item 'foo foo foo'. (you can assume the library of your choice is | |
// available) | |
var myArray = [ 'foo', 'bar', 'baz' ]; | |
var newMyArray = []; | |
for( var i = 0; i < myArray.length; i++ ) { | |
newMyArray[i] = "% % %".replace(/%/g, myArray[i]); | |
} | |
// 6: how could you improve the following code? | |
$(document).ready(function() { | |
$('.foo #bar').css('color', 'red'); | |
$('.foo #bar').css('border', '1px solid blue'); | |
$('.foo #bar').text('new text!'); | |
$('.foo #bar').click(function() { | |
$(this).attr('title', 'new title'); | |
$(this).width('100px'); | |
}); | |
$('.foo #bar').click(); | |
}); | |
function onBarClick() { | |
$(this) | |
.attr('title', 'new title') | |
.width('100px'); | |
} | |
$('.foo #bar') | |
.css({ | |
'color': 'red', | |
'border': '1px solid blue' | |
}) | |
.text('new text') | |
.click(onBarClick) | |
.click(); | |
/* | |
I prefer to put click handlers in functions with proper semantic names, the | |
name depends on what the code wants to achieve... | |
Obs: I'm not really a jQuery user.. | |
*/ | |
// 7: what issues do you see with the following code? how would you fix it? | |
(function() { | |
var foo; | |
dojo.xhrGet({ | |
url : 'foo.php', | |
load : function(resp) { | |
foo = resp.foo; | |
} | |
}); | |
if (foo) { | |
// run this important code | |
} | |
})(); | |
/* | |
foo might be undefined at the time of if() so that bit of important code might | |
never be executed. | |
to fix it i guess it depends on the objective of the code, put the important | |
code in a function and call it inside the load I would say. | |
*/ | |
// 8: how could you rewrite the following code to make it shorter? | |
(function(d, $){ | |
$('li.foo a').attr('title', 'i am foo'); | |
$('li.bar a').attr('title', 'i am bar'); | |
$('li.baz a').attr('title', 'i am baz'); | |
$('li.bop a').attr('title', 'i am bop'); | |
})(dojo, dojo.query); | |
(function(d, $){ | |
d.forEach(['foo', 'bar', 'baz', 'bop'], function(className) { | |
$('li.'+className+' a').attr('title', 'i am '+className); | |
}); | |
})(dojo, dojo.query); | |
/* | |
Obs: I'm not really a dojo user.. | |
*/ | |
// 9: how would you improve the following code? | |
for (i = 0; i <= 100; i++) { | |
$('#thinger').append('<p><span class="thinger">i am thinger ' + i + '</span></p>'); | |
$('#gizmo').append('<p><span class="gizmo">i am gizmo ' + i + '</span></p>'); | |
} | |
var i = 0; | |
var tmpl = '<p><span class="%name">i am %name %i</span></p>'; | |
var numStr = new Array(101).join(tmpl).replace(/%i/g, function() { return i++; }); | |
$('#thinger').append(numStr.replace(/%name/g, "thinger")); | |
$('#gizmo').append(numStr.replace(/%name/g, "gizmo")); | |
/* | |
optionally: | |
['thinger', 'gizmo'].forEach(function(e) { | |
$('#'+e).append(numStr.replace(/%name/g, e)); | |
}); | |
*/ | |
/* | |
It kind of sucks but I found it funny, it does avoid changing the DOM 100's of | |
times. | |
I have no idea if it's faster, there is no string concatenation in js at least, | |
hopefully the native join/replace implementations will be faster... | |
*/ | |
// 10: a user enters their desired tip into a text box; the baseTotal, tax, | |
// and fee values are provided by the application. what are some potential | |
// issues with the following function for calculating the total? | |
function calculateTotal(baseTotal, tip, tax, fee) { | |
return baseTotal + tip + tax + fee; | |
} | |
/* | |
god knows what the user typed in, anything from letters to negative numbers | |
that might make the total <= 0. | |
*/ | |
// 11: given the following data structure, write code that returns an array | |
// containing the name of each item, followed by a comma-separated list of | |
// the item's extras, if it has any. e.g. | |
// | |
// [ "Salad (Chicken, Steak, Shrimp)", ... ] | |
// | |
// (you can assume the library of your choice is available) | |
var menuItems = [ | |
{ | |
id : 1, | |
name : 'Salad', | |
extras : [ | |
'Chicken', 'Steak', 'Shrimp' | |
] | |
}, | |
{ | |
id : 2, | |
name : 'Potato', | |
extras : [ | |
'Bacon', 'Sour Cream', 'Shrimp' | |
] | |
}, | |
{ | |
id : 3, | |
name : 'Sandwich', | |
extras : [ | |
'Turkey', 'Bacon' | |
] | |
}, | |
{ | |
id : 4, | |
name : 'Bread' | |
} | |
]; | |
var result = []; | |
for( var i = 0, item; item = menuItems[i]; i++ ) { | |
result.push(item.name + (item.extras ? '('+item.extras.join(', ')+')' : ''); | |
} | |
return result; | |
// BONUS: what is the faulty logic in the following code? how would you fix it? | |
var date = new Date(), | |
day = date.getDate(), | |
month = date.getMonth(), | |
dates = []; | |
for (var i = 0; i <= 5; i++) { | |
dates.push(month + '/' + (day + i)); | |
} | |
console.log('The next five days are ', dates.join(', ')); | |
/* | |
If the start day is, say, 30, it will report day 33, 34 for instance, which | |
doesn't exist. | |
A possible fix is to increment the date object itself and getDate() and | |
getMonth() at every loop iteration. | |
Also, if we want to report the -next- five days I guess it should start at i = | |
1, that loop as it is, is creating a 6 item array. | |
*/ | |
var date = new Date(), | |
dates = [], | |
dayInMs = 24*60*60*1000; | |
for (var i = 0; i < 5; i++) { | |
date.setTime(date.getTime() + dayInMs); | |
dates.push(date.getMonth() + '/' + date.getDate()); | |
} | |
console.log('The next five days are ', dates.join(', ')); |
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