Some Important methods of Javascript, mostly useable…

Javascript String, Number, Math

1. indexOf(): In an array or object to find out number or word’s position, we use indexOf. If the indexOf’s value is -1 that means it doesn’t find anything like what is searching. Example:
   const friends =[‘Rahim’, ‘Karim’, ‘Kamal’, ‘Jamal’, ‘Abul]; console.log(friends.indexOf(‘Kamal’));
   Output is: 2;
2. replace(): If we need to change any word or number in an array or object, we can easily change it by replace() method. Example:
   const comment = “The quick brown fox jump over the lazy dog”; console.log(comment.replace(‘dog’, ‘cat’));
   Output is: ‘The quick brown fox jump over the lazy dog.’
3. slice(): Sometimes we want to keep some particular items removing others items. Then we can do that by slice(). Example:
   const fruits = [‘banana’, ‘apple’, ‘orange’, ‘watermelon’, ‘mango’]; console.log(fruits.slice(2));
   Output is: [‘orange’, ‘watermelon’, ‘mango’]
4. toUppercase(): Making capital letter our article’s all words or any specific word toUppercase is the simple way.
   const sentence = ‘Bangladesh is my homeland’; console.log(sentence.toUppercase());
   Output is: ‘BANGLADESH IS MY HOMELAND’;
5. toLowercase(): To convert all words into smaller word we can use toLowercase. Example:
   const sentence = “I love Bangladesh”; console.log(sentence.toLowercase());
   Output is: “i love bangladesh”;
6. isNaN: Calculating any math if we give any input against number to letter which means nothing then output comes NaN(not a number). Example:
   var x = 5;
   var y = a;
   console.log(x/y);
   Output is: NaN;
7. parseFloat(): Convert number into string, parseFloat is used. If we use parseFloat, it calculate the all inputed funtionality then make the result into string. Let’s have a look by a example:
   function result(num){
   parseFloat(num) * 5;
   console.log(result(10))
   Output is: ‘50’
   }
8. parseInt(): parseInt() is used to covert any string into integer number. Example:
   var a = ‘20.12’;
   result = (parseInt(a));
   console.log(result);
   Output is: 20;
9. Math.floor(): In this method decimal number converts into less integer number. If we use Math.floor() in a decimal number, it reduces the all decimal number after the integer number and return just integer number. Example:
   var x = 12.12;
   result = Math.floor(x);
   console.log(result);
   Output is: 12;
10. Math.ceil(): It converts decimal number into more integer number. If we use Math.ceil() in a decimal number, it increases the decimal number and returns larger integer number. Example:
    var x = 12.14;
    result = Math.ceil(x);
    console.log(result);
    Output is: 13;