Introduction
JavaScript is a lightweight and flexible programming language of the web. It powers the dynamic behavior on most websites. JavaScript is just-in-time compiled programming language. So here are some tips and tricks for JavaScript.
Unique Value Filter on Array
An array is an object that can store multiple values at once. For example,
const array = [1,2,3]
The array is storing 3 values.
Create an Array
Using an array literal
const array1 = ["eat", "sleep"];
Using the new keyword
const array2 = new Array("eat", "sleep");
Now if we want to find unique values then we can use,
const array = [1,1,2,3,6,6,3,1]
const uniArray = [...new Set(array)];
console.log(uniArray);
Output
[1,2,3,6]
Filter Array on condition
let array = ["The","Coding","Master"];
console.log(array.filter(x=>x.length >3));
Output
["Coding", "Master"]
Check item availability in Array
let array = ["The","Coding","Master"];
console.log(array.includes("The"));
Output
true
Truncate Array
let array = [0,1,2,3,4,5];
array.length=3;
console.log(array);
Output
[0,1,2]
Last Item in Array
let a= [0,1,2,3];
console.log(a.slice(-1));
Output
[3]
Join All Item from Array
let arr= ['a','b','c','d'];
console.log(arr.join("-"));
Output
"a-b-c-d"
Converts Array to string
const arr = ['hello','js'];
console.log(arr.toString());
Output
"hello,js"
Concat Array in Array
let arr= ['a','b'];
console.log(arr.concat(['c']));
Output
["a", "b", "c"]
Index Of Item in Array
let arr= ['a','b','c'];
console.log(arr.indexOf('c'));
Output
2
Last Index Of Item in Array
let arr= ['a','b','a'];
console.log(arr.lastIndexOf('a'));
Output
2
Manipulate Item in Array
let arr= [1,2,3];
console.log(arr.map(x=>x*2));
Output
[2, 4, 6]
Reverse Array
let arr= [1,2,3];
console.log(arr.reverse());
Output
[3, 2, 1]
Sort Array
let arr= [22,15,13];
console.log(arr.sort());
Output
[13, 15, 22]
Remove last Item in Array
let arr= [22,15,13];
console.log(arr.pop());
Output
13
Push Item in Array
let arr= [22,15,13];
arr.push(8);
console.log(arr);
Output
[22, 15, 13, 8]
Push Item in Array
let arr= [22,15,13];
arr.push(8);
console.log(arr);
Output
[22, 15, 13, 8]
Remove first Item in Array
let arr= [2,1,3];
arr.shift();
console.log(arr);
Output
[1,3]
Add new Item in Array to beginning
let arr= [2,1,3];
arr.unshift(0);
console.log(arr);
Output
[0, 2, 1, 3]
Get a portion of Array into new Array
const arr = ['q','w','e','r','t',];
const arr1 = arr.slice(1, 3);
console.log(arr1);
Output
["w", "e"]
Add Item in specified way and position in Array
const arr = ['q','w','e','r','t',];
arr.splice(3, 0, "l", "k");
console.log(arr);
Output
["q", "w", "e", "l", "k", "r", "t"]
const arr = ['q','w','e','r','t',];
arr.splice(3, 3, "l", "k");
console.log(arr);
Output
["q", "w", "e", "l", "k"]
Foreach() on Array
let array = ["The","Coding","Master"];
let text="";
array.forEach(myFunction);
console.log(text);
function myFunction(item, index) {
text += index + ": " + item + " ";
}
Output
"0: The 1: Coding 2: Master "
Every() on Array
const arr = [32, 33, 16, 40];
console.log(arr.every(check));
function check(item) {
return item > 18;
}
Output
false
Some() on Array
const arr = [3, 10, 18, 20];
console.log(arr.some(check));
function check(item) {
return item > 18;
}
Output
true
Convert to Boolean
const t= !0;
const f= !!0;
console.log(t);
console.log(f);
Output
True and False
Convert to String
const val = 3+ "";
console.log(val);
Output
"3"
Convert to Number to local language string
let num = 1234567;
let text = num.toLocaleString("hi-IN");
console.log(text );
Output
12,34,567
In JavaScript, numbers are primitive data types. Unlike in some other programming languages, you don't have to specifically declare for integer or floating values using int, float, etc.
Here is a list of built-in number methods in JavaScript.
| Method |
Description |
| isNaN() |
determines whether the passed value is NaN |
| isInteger() |
determines whether the passed value is an integer |
| parseFloat(string) |
converts the numeric floating string to floating-point number |
| toPrecision() |
returns a string value for a number to a specified precision |
| valueof() |
returns the numbers value |
Convert to Int
let s= "16";
s = +s;
console.log(s);
Output
"16"
Convert Float to Int
const f = 11.5 | 0;
console.log(f);
Output
"11"
Remove last digits
const c = 1553/10| 0;
console.log(c);
Output
"155"
Format number to specified length
let num = 0.1264;
console.log(num.toPrecision(2));
console.log(num.toPrecision(3));
Output
Summary
A short summary of JavaScript's tips and tricks for beginners, including different kinds of JS objects, basic data structures, and how we can play with them as well as use JavaScript to build dynamic web pages and web applications.