If Var A = True Then A == 1 Is True But A == 2 Is False. Why?

if var a = true then a == 1 is true but a == 2 is false. Why? I understand that in javascript boolean expressions 0 casts to false and 1 casts to true. But what about the other

Solution 1:

Why? I understand that in javascript boolean expressions 0 casts to false and 1 casts to true.

Because Number(true) => 1

As per spec of abstract equality expression evaluation

8. If Type(x) is Boolean, return the result of the comparison ToNumber(x) == y.

Hence a is first coerced into a Number and then compared with 1.

Solution 2:

when you use == or != in js,the operands will be converted to the same type before making the comparison.when converting:

if there is a Boolean, true will be turned to 1 and false turned to 0;

var a = true;
    a == 1;// a turned to 1 before compare,so true
    a == 2;// a turned to 1 before compare,so false

Solution 3:

This is to do with coercion. In the a == 1 scenario, a is coerced into a an integer to compare again 1, true is coerced to 1. In the second example, a is again coerced to 1, so it doesn't equal 2.

Further reading on coercion

Solution 4:

You may convert 1 to True and True to 1 but you can't convert other numerics to True.

Solution 5:

That's probably inherited from binary world and it makes sense, because in binary 0 is false and 1 is true. Exactly, that is how type conversion been done for boolean types in javascript as well while comparing.

For boolean there are only 2 possibles, true or false. Hence in number/binary system 0 and 1 are apt to represent them.