libgo/go/time/zoneinfo_js.go

   1 // Copyright 2018 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build js,wasm
   6
   7 package time
   8
   9 import (
  10         "runtime"
  11         "syscall/js"
  12 )
  13
  14 var zoneSources = []string{
  15         "/usr/share/zoneinfo/",
  16         "/usr/share/lib/zoneinfo/",
  17         "/usr/lib/locale/TZ/",
  18         runtime.GOROOT() + "/lib/time/zoneinfo.zip",
  19 }
  20
  21 func initLocal() {
  22         localLoc.name = "Local"
  23
  24         z := zone{}
  25         d := js.Global().Get("Date").New()
  26         offset := d.Call("getTimezoneOffset").Int() * -1
  27         z.offset = offset * 60
  28         // According to https://tc39.github.io/ecma262/#sec-timezoneestring,
  29         // the timezone name from (new Date()).toTimeString() is an implementation-dependent
  30         // result, and in Google Chrome, it gives the fully expanded name rather than
  31         // the abbreviation.
  32         // Hence, we construct the name from the offset.
  33         z.name = "UTC"
  34         if offset < 0 {
  35                 z.name += "-"
  36                 offset *= -1
  37         } else {
  38                 z.name += "+"
  39         }
  40         z.name += itoa(offset / 60)
  41         min := offset % 60
  42         if min != 0 {
  43                 z.name += ":" + itoa(min)
  44         }
  45         localLoc.zone = []zone{z}
  46 }
  47
  48 // itoa is like strconv.Itoa but only works for values of i in range [0,99].
  49 // It panics if i is out of range.
  50 func itoa(i int) string {
  51         if i < 10 {
  52                 return digits[i : i+1]
  53         }
  54         return smallsString[i*2 : i*2+2]
  55 }
  56
  57 const smallsString = "00010203040506070809" +
  58         "10111213141516171819" +
  59         "20212223242526272829" +
  60         "30313233343536373839" +
  61         "40414243444546474849" +
  62         "50515253545556575859" +
  63         "60616263646566676869" +
  64         "70717273747576777879" +
  65         "80818283848586878889" +
  66         "90919293949596979899"
  67 const digits = "0123456789"