Understanding JavaScript Truthy and Falsy

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深忆病人
深忆病人 2020-11-22 08:20

Can someone please explain JavaScript Truthy and Falsy, using the below sample data. I have read other threads but still confused.

var a = 0;

var a = 10 ==          


        
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  •  天涯浪人
    2020-11-22 08:52

    From my understanding, I believe that var a = 1; is the only truthy and the rest are falsy’s - is this correct?

    No.

    1. var a = 0;

      Number zero is falsy. However, note that the string zero "0" is truthy.

    2. var a = 10 == 5;

      This is same as var a = (10 == 5);, so this is falsy.

    3. var a = 1;

      var a = -1;

      Any non-zero number including negative numbers is truthy.

    Quoting from MDN

    In JavaScript, a truthy value is a value that translates to true when evaluated in a Boolean context. All values are truthy unless they are defined as falsy (i.e., except for false, 0, "", null, undefined, and NaN).

    List of falsy values in JavaScript:From MDN

    1. false
    2. null
    3. undefined
    4. 0
    5. NaN
    6. '', "", ``(Empty template string)
    7. document.all
    8. 0n: BigInt
    9. -0

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