Javascript - convert binary to decimal

Question

I'm using the solution provided here Read bit value to convert 1 byte (8 bit - unsigned number from 0 to 255) to a boolean array, E.g 118 gives me:

boolArray = [false, true, true, false, true, true, true, false]

Now I need to convert it back to the decimal representation, If i create a binary from boolArray like this:

    binObj = []
    OutObj.map((obj) => {
      BoolToInt = obj.isActive ? 1 : 0
      binObj.push(BoolToInt)
    })
    binary = binObj.toString().replaceAll(',', '') // =>  01101110

how can I convert the binary "01101110" to decimal value 118?

If I use parseInt the result is 110 not 118

 parseInt('01101110', 2) => 110

am I doing something wrong?

I would get back 118 from 01101110, not 110.

FYI, "false", "true" are strings, (not boolean false, true) and will all evaluate to true. — Roko C. Buljan
– Roko C. Buljan, Commented Dec 12, 2022 at 9:06
Well 1101110 is 110 and not 118. (1*64+1*32+0*16+1*8+1*4+1*2+0*1 = 64+32+8+4+2 = 110). 118 is the reverted direction 1110110. read the array backwards. — MoxxiManagarm
– MoxxiManagarm, Commented Dec 12, 2022 at 9:10

Andrew Parks · Accepted Answer · 2022-12-12 09:51:29Z

3

A more compact way of doing decimal<->binary boolean arrays:

console.log([...(118).toString(2)].map(i=>i==='1'))
console.log(
  parseInt([true,true,true,false,true,true,false].map(i=>+i).join(''),2)
)

edited Dec 12, 2022 at 9:51

answered Dec 12, 2022 at 9:37

Andrew Parks

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1 Comment

Ivar Over a year ago

Number() isn't really necessary here because 118 already is a number. [...(118).toString(2)] or [...118..toString(2)] will do.

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