Hello friends, In this article, we will learn Type coercion, explicit type coercion and implicit type coercion in javascript.
Type coercion is the process of converting value from one type to another for example string to number, number to boolean, object to boolean etc.
Type coercion can be of two types explicit type coercion and implicit type coercion.
Explicit Type Coercion:
When a we converts between types like Number(value) , parseInt(value) , parseFloat(value) etc. it’s called explicit type coercion or type casting.
Implicit Type Coercion:
We knows JavaScript is a weakly-typed language, values can also be converted between different types automatically, and it is called implicit type coercion.
Example:
String(4512) // explicit
4512 + '' // implicit
Number('123') // explicit
+'123' // implicit
123 != '456' // implicit
4 > '5' // implicit
5/null // implicit
true | 0 // implicit
More Implicit Type Coercion:
"number" + 16 + 3 // 'number163'
16 + 4 + "number" // '20number'
true + false // 1
12 / "6" // 2
[1] > null // true
'true' == true // false
false == 'false' // false
null == '' // false
!!"false" == !!"true" // true
['x'] == 'x' // true
[1,2,3] == [1,2,3] // false
"SWC" + + "bar" // 'SWCNaN'
[] + null + 1 // 'null1'
{}+[]+{}+[1] // '0[object Object]1'
!+[]+[]+![] // 'truefalse'
new Date(0) - 0 // 0
new Date(0) + 0 // 'Thu Jan 01 1970 02:00:00(EET)0'
"!=" operator is known as type coercion operator and "!==" is known as strictly equality operator. it's important to know which operator is used for which operation.
"!=" operator compares variable by their values.
Where as "!==" operator not only checks the value of variable, moreover it compares variable by making their type correction.
Following examples will make it simple to understand.
var n = 12;
var s = "12";
document.write("n != s returns " + (n!=s) +"<br />");
document.write("n !== s returns " + (n!==s));
OUTPUT: n != s returns false n !== s returns true
Explanation:
Since n is of numeric type. and s is string. "!=" operator converts both variable into same type then compares. while "!==" operator first compares their types then their values.
Example:
var n = 0;
var b = false;
document.write("n != b returns " + (n!=b) +"<br />");
document.write("n !== b returns " + (n!==b));
OUTPUT: n != b returns false n !== b returns true
Explanation:
Since n is of numeric type. and b is boolean. "!=" operator converts both variable into same type then compares returns false.
while "!==" operator first compares their types then their values returns true.
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