Why parseFloat in javascript returns string type for me?

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甜味超标
甜味超标 2021-01-06 07:22

I searched and only found this one related to my question, but not exactly the same, as I\'m using toFixed rather than toPrecision. Why does toPrecision return a String?

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  • 2021-01-06 07:56

    The Number.prototype.toFixed() function is supposed to return a string type as per the documentation found here.

    If you need to perform further arithmetic with the number you can coerce it back into numeric form using the Unary plus operator before the variable name (+) documented here like so:

    var oldv = parseFloat(document.getElementById('total').textContent).toFixed(2);
    
    alert(typeof oldv); // Returns string
    
    alert(typeof +oldv); // Returns number
    
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  • 2021-01-06 08:07

    As mentioned in docs, toFixed returns

    A string representing the given number using fixed-point notation

    In case you need to use the returned result as a number, you can use built-in object Number:

    var oldv = parseFloat(Math.PI).toFixed(2);
    
    console.log( oldv );
    console.log( typeof oldv ); // returns string
    
    var num = Number(oldv);
    console.log( num );
    console.log( typeof num );  // returns number

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