Week 5 Section 4

by Ramya Ranganathan

HTML

<input id="input" type="text"/><br>
<div class="border" id="output"></div>
<h3>Functions!</h3>
<h4>Creating</h4>
<ul>
    <li>how to declare functions</li>
    <li>how not to declare functions</li>
    <li>return, multiple returns, no return</li>
</ul>
<h4>Why?</h4>
<ul>
    <li>DRY</li>
    <li>organization</li>
</ul>
<h4>Scope</h4>
<ul>
    <li>global</li>
    <li>var</li>
    <li>function scope</li>
</ul>

CSS

.hide {
    display: none;
}
.border {
    border: 1px solid blue;
}

JavaScript

// creating
// no return
function logMessage(msg){ }

// using %
var isEven = function(num){ }

// using isEven
var isOdd = function(num){ }

var getEvenSum = function(numArray){ }


// why?
var output = document.getElementById("output");
output.innerHTML += "The sum of the even numbers is: <br>";
console.log("The sum of the even numbers is: ");


var arr = [1, 2, 3, 4, 5, 6];
var evenSum = 0;
for(var i = 0; i < arr.length; i++){
    if(arr[i] % 2 == 0){
        evenSum += arr[i];
    }
}
output.innerHTML += evenSum;
console.log(evenSum);



// scope
var k = "harvard";

var myfunc  = function(word) {
	word = "yale";
	return word;
}
k = myfunc("anything");
// what is k?

var k = 10;
var myfunc2 = function(num){
    var k = 11;
}
k = myfunc2(k);
// what is k?

var k = "word";
var myfunc3 = function(){
    k += " to your mother";
}
myfunc3();
// what is k?

var myfunc4 = function(){
    var k = "something";
}
myfunc4();
// what is k?

var myfunc5 = (function(){
    k = "flibberty";
})();
// what is k?



if(document.getElementById("output").innerHTML == ''){
    document.getElementById("output").className = "hide";
} else {
    document.getElementById("output").className = "";
}