JavaScript — Type Conversion

Type conversion is the process of converting data of one type to another. For example:-
1. Convert Strings to Numbers
2. Convert Numbers to Strings
3. Convert Strings to Decimals
4. Covert Numbers to Booleans
5. Covert Booleans to Numbers
6. Convert Dates to Numbers

Convert Strings to Numbers

parseInt()
In the following example, we created a string variable called value and assign it to 20. When you use ‘typeof’ we can see it shows as a string on the console.

parseInt() — Convert string to numbers

Unary Plus (+)

Number() method

Convert Number to String

toString() method

String() constructer

Convert Strings to Decimals

parseFloat()

Convert Number to Boolean

Boolean is true or false value.

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let value = "2";

value = Boolean(value);

console.log(value, typeof value);

If I set this value to ‘0’ then you can see the output as ‘false’. Because zero is a false value. Zero is the only number gives output as false.

let value = 0;

value = Boolean(value);

console.log(value, typeof value);

Let’s see what happened if we tried to take a string that is not a number. If I pass this to number.

let value = "Thanks";

value = parseInt(value);

console.log(value, typeof value);

We get the value of ‘NaN’. This stands for ‘Not A Number’.

NaN is a property of the global window object. There are other types of operators that can return NaN.

console.log(Math.sqrt(-4));

console.log(4 + NaN);

console.log(undefined + undefined); - Output - NaN

console.log("Hi" / 2); - Output - NaN

Convert Dates to Numbers

The global method Number() can be used to convert dates to numbers.

convert dates to numbers.

The date method getTime() does the same.