var str = '0.25';
How to convert the above to 0.25?
4 Answers
There are several ways to achieve it:
Using the unary plus operator:
var n = +str;
The Number constructor:
var n = Number(str);
The parseFloat function:
var n = parseFloat(str);
answered Jan 25, 2010 at 5:52
Christian C. Salvadó
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2 Comments
Justin Johnson
Also, for integers (only), there's
~~str and str | 0
Ben
Without knowing the implications and side effects of each of these, I'd opt for
Number(str) as it's the most readable & interpretable code.For your case, just use:
var str = '0.25';
var num = +str;
There are some ways to convert string to number in javascript.
The best way:
var num = +str;
It's simple enough and work with both int and float
num will be NaN if the str cannot be parsed to a valid number
You also can:
var num = Number(str); //without new. work with both int and float
or
var num = parseInt(str,10); //for integer number
var num = parseFloat(str); //for float number
DO NOT:
var num = new Number(str); //num will be an object. (typeof num == 'object') will be true.
Use parseInt only for special case, for example
var str = "ff";
var num = parseInt(str,16); //255
var str = "0xff";
var num = parseInt(str); //255
Comments
var num = Number(str);
Comments
var f = parseFloat(str);
parseIntis blazing fast, but if you need decimals, you should go withparseFloat: jsbench.me/pokty2hchw/1'0.25'*1is about 98% faster thanparseFloat()jsbench.me/bflb5lcqpw/1parseFloat()performs about 15% better than''*1: jsbench.me/c8ldyhrth3/1