javascript - Why does ~-1 equal 0 and ~1 equal -2? -

according subsection 11.4.8 of ecmascript 5.1 standard:

the production unaryexpression : ~ unaryexpression evaluated follows:

1. let expr result of evaluating unaryexpression.
2. let oldvalue toint32(getvalue(expr)).
3. return result of applying bitwise complement oldvalue. result signed 32-bit integer.

the ~ operator invoke internal method toint32. in understanding toint32(1) , toint32(-1) return same value 1 , why ~-1 equal 0 , ~1 equal -2?

now question why toint32(-1) equals -1? subsection 9.5 of ecmascript 5.1 standard:

the abstract operation toint32 converts argument 1 of 2³² integer values in range −2³¹ through 2³¹−1, inclusive. abstract operation functions follows:

1. let number result of calling tonumber on input argument.
2. if number nan, +0, −0, +∞, or −∞, return +0.
3. let posint sign(number) * floor(abs(number)).
4. let int32bit posint modulo 2³²; is, finite integer value k of number type positive sign , less 2³² in magnitude such mathematical difference of posint , k mathematically integer multiple of 2³².
5. if int32bit greater or equal 2³¹, return int32bit − 2³², otherwise return int32bit.

when argument -1,according 9.5, in step 1 number still -1, skip step2 in step 3 posint -1 in step 4 int32bit 1 in step 5 return 1

which step wrong?

the -1 in 32-bit integer

1111 1111 1111 1111 1111 1111 1111 1111 

so ~-1 be

0000 0000 0000 0000 0000 0000 0000 0000 

which zero.

the 1 in 32-bit integer

0000 0000 0000 0000 0000 0000 0000 0001 

so ~1 be

1111 1111 1111 1111 1111 1111 1111 1110 

which -2.

you should read two's complement understand display of negative integer in binary-base.