CODEWITHSUNDEEP
javascriptjquerycoffeescript
CamelCamelCamel
CamelCamelCamel

Reputation: 5200

JavaScript - Convert Long Number to String

"" + 237498237498273908472390847239084710298374901823749081237409273492374098273904872398471298374
> '2.3749823749827392e+92'

I calculate IDs in a beautiful and arcane way:

time = new Date().getTime()
pid = process.pid
host = 0; (host +=s.charCodeAt(0) for s in os.hostname())
counter = MIPS.unique_id()

"#{host}#{pid}#{time}#{counter}"

Unfortunately, somewhere along the way the IDs (for example 11207648813339434616800). Unfortunately this means they sometimes turn to 1.1207648813339434e+22.

UPDATE:

It seems to be a "bug/feature" of redis. never expected that.

# Bug with Big Numbers on zadd
redis = require 'redis'
r = redis.createClient()
r.zadd 'zset', '342490809809999998098', 'key', ->
    r.zscore 'zset', 'key', (_, results) ->
        console.log typeof results # string
        console.log results # 3.4249080981000002e+20

Upvotes: 3

Views: 2377

Answers (2)

Zang MingJie
Zang MingJie

Reputation: 5275

Javascript use 8-bytes double to store large numbers, which is 53bit precision. In your case, it is far beyond 53 bits, so you should use a big-number library, which can store big numbers precisely. Try javascript-bignum

Upvotes: 2

Blender
Blender

Reputation: 298106

Your number gets converted to 2.3749823749827392e+92 before you concatenate the number with the string to convert it.

The only solution is to use a container format that accepts an arbitrary number of digits, which is either a string or an array.

Can you provide us with a few more details as to how you are obtaining this number?

Upvotes: 1

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