1. Using parseInt()
parseInt() parses a string and returns a whole number. Spaces are allowed. Only the first number is returned.
This method has a limitation though. If you parse the decimal number, it will be rounded off to the nearest integer value and that value is converted to string. One might need to use parseFloat() method for literal conversion.
myString = '129'
console.log(parseInt(myString)) // expected result: 129
a = 12.22
console.log(parseInt(a)) // expected result: 12
2. Using Number()
Number() can be used to convert JavaScript variables to numbers. We can use it to convert the string too number.
If the value cannot be converted to a number, NaN is returned.
Number("10"); // returns 10
Number(" 10 "); // returns 10
Number("10.33"); // returns 10.33
3. Using Unary Operator (+)
The unary plus operator (+) precedes its operand and evaluates to its operand but attempts to convert it into a number, if it isn't already.
const x = 25;
const y = -25;
console.log(+x); // expected output: 25
console.log(+y); // expected output: -25
console.log(+''); // expected output: 0
4. Using parseFloat()
parseFloat() parses a string and returns a number. Spaces are allowed. Only the first number is returned.
parseFloat("10"); // returns 10
parseFloat("10.33"); // returns 10.33
parseFloat("10 20 30"); // returns 10
parseFloat("10 years"); // returns 10
parseFloat("years 10"); // returns NaN
5. Using Math.floor()
The Math.floor() function returns the largest integer less than or equal to a given number. This can be little tricky with decimal numbers since it will return the value of the nearest integer as Number.
str = '1222'
console.log(Math.floor(str)) // returns 1222
a = 12.22
Math.floor(a) // expected result: 12
6. Multiply with number
Multiplying the string value with the 1 which won’t change the value and also it will be converted to number by default.
str = '2344'
console.log(str * 1) // expected result: 2344
7. Double tilde (~~) Operator
We can use the double tilde operator to convert the string to number.
str = '1234'
console.log(~~str) // expected result: 1234
negStr = '-234'
console.log(~~negStr) // expected result: -234
Here is the comparison of the ways mentioned performance wise. Comment below if you know more methods.
Thank You
Top comments (21)
The double tilde method is actually something I never thought about, but is worth explaining.
The double tilde "operator" is not as much as an operator as it's a double bitwise negation.
Let's cast
'64'to64using this method, so we do~~'64'. First we will evaluate~'64'. As bitwise operations work on binary,'64'is cast to a number. So~64.64in binary is01000000.~will negate all the bits so it becomes10111111, which is-65since numbers in JavaScript are signed. Now we negate it again, which becomes01000000, which is64in decimal.Correction:
I previously stated that
10111111is-63, which is incorrect. It's actually-65. Sorry about that.Thanks for explaining this. When I got to that one, I was wondering what it was. Great explanation.
Thank you. This was informative. I didn't pay attention about how it works while writing. Will note it down.
You should always pass the base as second argument to
parseInt.This is a really helpful article! As a beginner in JavaScript, I often find myself struggling with converting strings to numbers. It's great to see all these different methods laid out with examples for each one. I especially appreciated the explanation of the parseFloat() function and the caution against using the unary plus operator on strings that could be mistaken for numbers. Thank you for sharing! FitGAG
In the first paragraph "If you parse the decimal number, it will be rounded off to the nearest integer value and that value is converted to string. " I think it should say "that value is converted to a number".
Cupcake 2048 is a delightful twist on the classic 2048 game, where you combine cupcakes to create even more delicious treats. It's a fun and addictive way to pass the time! You can play it 2048 cupcakes.
Enjoy the sweetness of 2048 cupcakes!
The headline says: "If candy clicker parse the decimal number, it will be rounded off to the nearest integer value and that value is converted to string." I believe that the statement "That value is converted to a number" should be added.
Choosing the best method depends on your specific needs. If you need an integer, use parseInt. If you need a floating-point number, use parseFloat. Number() is a good general-purpose option, while the unary plus operator and multiplication by 1 are convenient for quick conversions but might have unexpected behavior. Remember to handle potential NaN results for robustness. Slope 3 is so addictive! I can't stop trying to beat my high score
how would we go about converting a 19 digit string to a number , js behaves very weirdly for that
e.g lets say this is the number 6145390195186705543 and want to convert it into number what it gives me is this 6145390195186705000. not sure why
thanks for the info.
Noice
Some comments may only be visible to logged-in visitors. Sign in to view all comments.