The Harmony (EcmaScript 6) proposal includes the specification for arrow functions, AKA lambda expressions. Given this technology early stage you should check in advance whether the web browser you target supports it.
The following code sample includes the definition for few arrow functions (lambda expressions).
<!DOCTYPE html>
<html>
<head>
<title>simple lambda expressions in javascript</title>
</head>
<body>
<script type="text/javascript">
var funcA = num => 2*num;
var funcB = num => num%2==0;
var funcC = (num1,num2) => num1+num2;
var funcD = (num1,num2,num3) => {
var temp = num1+num2;
var result = temp * num3;
return result;
}
document.writeln("<br>"+"funcA(3)="+funcA(3));
document.writeln("<br>"+"funcB(6)="+funcB(6));
document.writeln("<br>"+"funcC(3,4)="+funcC(3,4));
document.writeln("<br>"+"funcD(2,3,4)="+funcD(2,3,4));
</script>
</body>
</html>
The following video clip overviews this code sample, shows its execution and explains it.
The following code sample shows how we can write shorter code by using lambda expressions when in a need to pass over a function to another function.
<!DOCTYPE html>
<html>
<head>
<title>useful lambda expression demo in javascript</title>
</head>
<body>
<script type="text/javascript">
function Student(frstname,lstname,avg,idnumber)
{
this.first = frstname;
this.last = lstname;
this.id = idnumber;
this.average = avg;
this.toString = function()
{
return this.first+" "+this.last+" "+this.id+" "+this.average;
};
}
var students = [
new Student("mosh","cohen",88,121212),
new Student("dave","levin",98,324232),
new Student("leha","lapid",78,434234),
new Student("roza","efrat",92,423234),
new Student("yoni","rabin",75,534243)
];
function filter(vec,func)
{
var result = new Array();
var j=0;
for(var i=0; i<vec.length; i++)
{
if(func(vec[i]))
{
result[j] = vec[i];
j++;
}
}
return result;
}
var vector = filter(students,ob => ob.average>80);
for(var i=0; i<vector.length; i++)
{
document.writeln("<br>"+vector[i].toString());
}
</script>
</body>
</html>
The following video clip overviews this code sample, shows its execution and explains it.
You can find more code samples, video clips and training material for learning this topic in my JavaScript Programming free course at http://abelski.lifemichael.com.
