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To count the number of occurrences of a character in a string, try to run the following code −ExampleLive Demo function displayCount() { setTimeout(function() { var str = document.getElementById('str1').value; var letter = document.getElementById('letter1').value; letter = letter[letter.length-1]; var lCount; for (var i = lCount = 0; i < str.length; lCount += (str[i++] == letter)); document.querySelector('p').innerText = lCount; return lCount; }, 50); } Enter String: Enter Letter: Click for Result result=
The best way to initialize a number in JavaScript is to initialize variables while declaring them. Through this, you can easily avoid undefined values.ExampleYou can try to run the following code to initialize a number −Live Demo var deptNum = 20, id = 005; document.write("Department number: "+deptNum);
The best way to convert a number to a string is using the toString() method, with different bases. The method has an optional parameter “radix”, which is used as a base (2, 8, 16) for a numeric value.ExampleYou can try to run the following code to convert a number to a string −Live Demo var num = 10; var val1 = num.toString(); var val2 = num.toString(2); var val3 = num.toString(8); var val4 = num.toString(16); document.write(val1 + "" + val2 + "" + val3 + "" + val4); Output10 1010 12 a
With JavaScript, use the % operator to get the decimal portion of a number.ExampleYou can try to run the following to get decimal portion −Live Demo var num1 = 5.3; var num2 = 4.2; var num3 = 8.6; document.write(num1 % 1); document.write(""+num2 % 1); document.write(""+num3 % 1); Output0.2999999999999998 0.20000000000000018 0.5999999999999996
Firstly convert your number to hexadecimal with leading zeros and then format it by adding dashes.ExampleYou can try to run the following code to format hexadecimal number −Live Demo var num = 32122; var myHex = ("000000000000000" + num.toString(16)).substr(-16); var resHex = myHex.substr(0, 8)+'-'+myHex.substr(8,4)+'-'+myHex.substr(12,4); document.write(resHex); Output00000000-0000-7d7a
Use the toString() method to covert the Number to string, then the length() method gives you length.ExampleYou can try to run the following code to learn how to get the length of a Number −Live Demo var num1 = 344; var num2 = 149856; document.write("Length of number "+num1+" = "+ num1.toString().length); document.write("Length of number "+num2+" = "+ num2.toString().length); OutputLength of number 344 = 3 Length of number 149856 = 6
NaN is a JavaScript property, which is Not-a-Number value. This shows it is not a legal number. Here’s the syntax −SyntaxNumber.NaNTo find out whether a number is NaN, use the Number.isNaN() or isNan() method. Here’s an example to check −ExampleLive Demo Check function display() { var a = ""; a = a + isNaN(434) + ": 434"; a = a + isNaN(-23.1) + ": -23.1"; a = a + isNaN('Hello') + ": 'Hello'"; a = a + isNaN(NaN) + ": NaN"; a = a + isNaN('') + ": ''"; a = a + isNaN(0) + ": 0"; a = a + isNaN(false) + ": false"; document.getElementById("test").innerHTML = a; }
To get dates in JavaScript, use the getTime() method. Forgetting the difference between two dates, calculate the difference between date and time.ExampleYou can try to run the following code to learn how to calculate a difference between two dates −Live Demo var dateFirst = new Date("11/25/2017"); var dateSecond = new Date("11/28/2017"); // time difference var timeDiff = Math.abs(dateSecond.getTime() - dateFirst.getTime()); // days difference var diffDays = Math.ceil(timeDiff / (1000 * 3600 * 24)); // difference alert(diffDays);
To get an integer in the string “abcde 30”, use the following regex in JavaScript, else it will return NaN. With that, use parseInt() to get the numbers with regex under String match() method −ExampleLive Demo var myStr = "abcdef 30"; var num = parseInt(myStr.match(/\d+/)) alert(num);
Use the toString() method to get the string representation of a number. You can try to run the following code to print a string representation of numbers like 20, -40, 15.5 −ExampleLive Demo var num1 = 25; document.write(num1.toString()+""); document.write((30.2).toString()+""); var num2 = 3; document.write(num2.toString(2)+""); document.write((-0xff).toString(2)); Output25 30.2 11 -11111111Above, you can see we added a parameter to the toString() method. This is an optional parameter, which allows you to add an integer between 2 and 36, which is the base for representing numeric values.