How to many ways to convert string to number in Javascript
Dung Do Tien
Feb 12 2020
496
In my sample app, I need to addition two number, one is string type and other number type.
<script>
var a = "5";
var b = 10;
alert(a + b)
</script>
I get result 510. How can I make it result to 15? How many way to do?
Have 1 answer(s) found.
-
M0
Manish Kumar Apr 03 2020
Hello,
In Javascript have some rule for addition(+) operator :
- string + string = string
- string + number = string
- string + bool = string
- string + datetime = string ....
And "5" + 10 = "510" is alright.
How to convert string to number? have some way bellow :
1. Use parseInt() Or parseFloat()
var a = "5"; a = parseInt(a) // return 5 and convert to integer number var b = "5.5"; b = parseFloat(b) // return 5.5 and convert to float data type2. Use Number() method
var age = Number("3") + 5; alert(age); // age = 83. Using operator + before value string.
var age =+"90"; alert(typeof age); // alert "number" var age1 =+"10"; alert(age + age1); // alert 1004. Using Multiply by 1(* 1)
var age ="90" * 1; alert(typeof age); // alert "number" var age1 ="10" *1; alert(age + age1); // alert 100So we have 4 ways to convert string to number in javascript. About performance, you can choose way 4 for the best performance.
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