JavaScript Inbuilt Functions

EXAMPLE

• JavaScript getDate

function getDay() {
    var date = new Date();
    var day = date.getDate();
    document.getElementById("sample").innerHTML = day;
}

• 
  
• JavaScript eval function

function evaluateExpression() {
    var x = 20;
    var y = 30;
    var a = eval("x * y") + "
";
    var b = eval("2 + 2") + "
";
    var c = eval("x + 17") + "
";
    var d = eval("18 + y") + "
";
    var result = a + b + c +d;
    document.getElementById("sample").innerHTML = result;
}

• Javascript isFinite function

• function isFiniteNumber() {
      var a = isFinite(4) + "
  ";
      var b = isFinite(-4) + "
  ";
      var c = isFinite(4-2) + "
  ";
      var d = isFinite(0) + "
  ";
      var e = isFinite("145") + "
  ";
      var f = isFinite("LearnKode") + "
  ";
  
      var result = a + b + c + d + e + f ;
      document.getElementById("sample").innerHTML = result;
  }

• 
  
• Javascript isNaN functions

• function checkNumber() {
      var a = isNaN(NaN) + "
  ";
      var b = isNaN(undefined) + "
  ";
      var c = isNaN(null) + "
  ";
      var d = isNaN(37) + "
  ";
       numbers=a+b+c+d;
       document.getElementById("sample").innerHTML = numbers;
  }

• 
  
• Javascript parseInt/Float functions

function convertToFloat() {
    var a = parseFloat("10") + "
";
    var b = parseFloat("10.00") + "
";
    var c = parseFloat("10.33") + "
";
    var d = parseFloat("34 45 66") + "
";
    var e = parseFloat("   60   ") + "
";
    var f = parseFloat("40 years") + "
";
    var g = parseFloat("I am 40") + "
";
    var result = a + b + c + d + e + f + g;
    document.getElementById("sample").innerHTML = result;
}

• 
  
• Javascript Objects

var person = {
    firstName : "Michael",
    lastName  : "Voughan",
    age       : 40,
    eyeColor  : "blue"
};
document.getElementById("sample").innerHTML =
person.firstName + " " + person.lastName;

• 
  
• 
  
• Javascript Number

• function convertToNumber() {
      var a = false;
      var b = true;
      var c = new Date();
      var d = "888";
      var e= "666 555";
      var result = 
      Number(a) + "
  " + 
      Number(b) + "
  " + 
      Number(c) + "
  " + 
      Number(d) + "
  " + 
      Number(e);
      document.getElementById("sample").innerHTML = result;
  }

• 
  
• JavaScript Date object

• var date = new Date("December 13, 2015 11:13:00");

• 
  
• JavaScript Math Object

• var result = Math.sqrt(16);
  document.getElementById("sample").innerHTML = result;

• 
  
• JavaScript Array

• var vehicles= ["Alto", "Swift", "BMW"];
  document.getElementById("sample").innerHTML = vehicles;

• 
  
• Javascript Comments

• // commented statements
  document.getElementById("mydiv").innerHTML = "My First Page";
  /*
  document.getElementById("mydiv").innerHTML = "My first paragraph.";
  */

• JavaScript Data types
• JavaScript special characters
• JavaScript if condition

• function dayGreeting() {
      var age = 19 
      var message;
      if (age < 18) {
          message = "You are not qualified for Voting";
      } else {
          message = "You are qualified for Voting";
      }
      document.getElementById("sample").innerHTML = message;
  }

• Javascript For Loop

   var count;
    document.write("Starting Loop" + "
");      
    for(count = 0; count < 10; count++){
    document.write("I am : " + count );
    document.write("
");
    }

    document.write("Loop stopped!");

• JavaScript While Statement

            document.write("Starting Loop ");
         
            while (count < 10){
               document.write("I am : " + count + "
");
               count++;
            }
         
            document.write("Loop stopped!");
        

• JavaScript Switch Case statement

var grade = 'A';
var message = '';
switch (grade) {
    case 'A':
        message = "Excellent";
        break;
    case 'B':
        message = "Good";
        break;
    case 'C':
        message = "OK";
        break;
    case 'D':
        message = "Mmmmm....";
        break;
    case 'E':
        message = "You must do better than this";
        break;
    default: 
        message = "What is your grade anyway?";
        break;
}
document.getElementById("sample").innerHTML =  message;

• JavaScript Exception handling

• try {
      ShowMessage("This function is not defined anywhere so it will go to catch statement and execute the statements of catch block.");
  }
  catch(err) {
      document.getElementById("sample").innerHTML = err.message;
  }

• JavaScript do while statement

var count = 0;
document.write("Here is the start of loop: " + "
");

do{
 document.write(" Counter : " + count + "
");
 count++;
} while (count < 10);

document.write ("End of loop!");

• JavaScript label statement

•   var a, b;
  
    outer:
    for (a = 0; a < 2; a++) {      
     inner:
     for (b = 0;b < 2; b++) {   
        if (a === 1 && b === 1) {
           continue outer;
        }
        document.write("a = " + a + ", b = " + b + "
  ");
     }
  }

• JavaScript break statement
• JavaScript continue statement
• JavaScript for in statement
• JavaScript function
• JavaScript Assignment operators
• JavaScript Comparison operators
• Javascript Arithmetic operators
• JavaScript Bitwise operators
• JavaScript Logical operators
• JavaScript String operators
• JavaScript Conditional operators

• function voteableAge() {
      var age, voteable;
      age = document.getElementById("age").value;
      voteable = (age < 18) ? "Too young":"Old enough";
      document.getElementById("sample").innerHTML = voteable + " to vote.";
  }
  </

• JavaScript typeof operator

•     function operatorFunction()
      {
  
      var val=5;    alert(typeof val);  
      
      }

• JavaScript void operator

•    Click the following, This won't react at all...

href="javascript:void(alert('Warning!!!'))">Click me!

JavaScript toExponential functional

JavaScript toFixed function

function convertToFixed() {
    var num = 6.76549;
    var exp = num.toFixed(3);
    document.getElementById("sample").innerHTML = exp;
}

• JavaScript toPrecision function
• JavaScript charCodeAt function
• JavaScript concat function

function joinArrays() {
    var cars = ["Alto", "Zen"];
    var buses = ["Punbus", "PePso", "Linus"];
    var result = cars.concat(buses); 
    document.getElementById("sample").innerHTML = result;
}

• JavaScript fromCharCode function
• JavaScript indexOf function

function findPosition() {
    var str = "Hello world, welcome to learnKode.";
    var n = str.indexOf("welcome");
    document.getElementById("sample").innerHTML = n;
}

• JavaScript lastIndexOf function
• JavaScript localeCompare function
• JavaScript match function

• function lastOccurance() {
      var str = "I like learnkode and i love learnkode.";
      var n = str.lastIndexOf("learnkode");
      document.getElementById("sample").innerHTML = n;
  }

function matchString() {
    var str = "I love learnKode that keeps my learning of code so easy."; 
    var result = str.match(/earn/g);
    document.getElementById("sample").innerHTML = result;
}

• JavaScript replace function

• function newString() {
      var str = document.getElementById("sample").innerHTML; 
      var result = str.replace("Google", "LearnKode");
      document.getElementById("sample").innerHTML = result;
  }

• JavaScript search function
• Javascript slice function

•     var vegs = ["Tomato", "Patato", "Lemon", "Cheese", "Carrot"];
      var result= vegs.slice(1, 4);
      document.write(result);

• JavaScript split function

• function splitString() {
      var str = "I Love LearnKode";
      var result = str.split(" ");
      document.getElementById("sample").innerHTML = result;
  }

• JavaScript substr function

•   function extractSubpart()
    {
       var str = "I Love LearnKode.";
       var result = str.substr(1, 5);
       document.getElementById("sample").innerHTML=result;
    }

• 
  
• JavaScript substring function

• function extractSubset() {
      var str = "i love learnkode";
      var result = str.substring(7, 16);
      document.getElementById("sample").innerHTML = result;
  }

• JavaScript toLocaleLowerCase function

• function convertToLowercase() {
      var str = "I LOVE LEARNKODE";
      var result = str.toLocaleLowerCase();
      document.getElementById("sample").innerHTML = result;
  }

• JavaScript toLocaleUpperCase function
• Javascript toString function
• JavaScript trim function
• JavaScript valueOf function

function convertToPrimitiveValue() {
    var str = "I love learnKode";
    var result = str.valueOf();
    document.getElementById("sample").innerHTML = result;
}

• JavaScript pop function

var fishName= ['angel', 'clown', 'mandarin', 'sturgeon'];
document.getElementById("sample").innerHTML = fishName;

function removeElement() {
    fishName.pop();
    document.getElementById("sample").innerHTML = fishName;
}

• JavaScript push function
• Adding elements at the end

• var arr= ['a', 'b','c','d'];
  document.getElementById("sample").innerHTML = arr;
  function addElement() {
      arr.push("e","f");
      document.getElementById("sample").innerHTML = arr;
  }

• JavaScript shift function

Removes first element of array

document.getElementById("sample").innerHTML = arr;

function removeElement() {
    arr.shift();
    document.getElementById("sample").innerHTML = arr;
}

• Adds 0 as first element of array

• document.getElementById("sample").innerHTML = arr ;
  
  function addElement() {
      arr.unshift(0);
      document.getElementById("sample").innerHTML = arr ;
  }

• JavaScript sort function
• 
  

var arr= ['ABC', 'XYX', 'BCD'];
document.getElementById("sample").innerHTML = arr;

function sortArray() {
    fruits.sort();
    document.getElementById("sample").innerHTML = arr;
}

• JavaScript reverse function

•    var arr= ['abc', 'xyz', 'def'];
     arr.reverse();
     document.write(arr);