fix: support timezoneOffset for date from scope, #401

src/builtin/filters/date.ts

@@ -1,8 +1,10 @@
-import strftime, { createDateFixedToTimezone } from '../../util/strftime'
+import strftime from '../../util/strftime'
 import { isString, isNumber } from '../../util/underscore'
 import { FilterImpl } from '../../template/filter/filter-impl'
+import { TimezoneDate } from '../../util/timezone-date'
 
 export function date (this: FilterImpl, v: string | Date, arg: string) {
+  const opts = this.context.opts
   let date: Date
   if (v === 'now' || v === 'today') {
     date = new Date()
@@ -11,15 +13,19 @@ export function date (this: FilterImpl, v: string | Date, arg: string) {
   } else if (isString(v)) {
     if (/^\d+$/.test(v)) {
       date = new Date(+v * 1000)
-    } else if (this.context.opts.preserveTimezones) {
-      date = createDateFixedToTimezone(v)
+    } else if (opts.preserveTimezones) {
+      date = TimezoneDate.createDateFixedToTimezone(v)
     } else {
       date = new Date(v)
     }
   } else {
     date = v
   }
-  return isValidDate(date) ? strftime(date, arg) : v
+  if (!isValidDate(date)) return v
+  if (opts.hasOwnProperty('timezoneOffset')) {
+    date = new TimezoneDate(date, opts.timezoneOffset!)
+  }
+  return strftime(date, arg)
 }
 
 function isValidDate (date: any): date is Date {

src/liquid-options.ts

@@ -6,7 +6,6 @@ import { FS } from './fs/fs'
 import * as fs from './fs/node'
 import { defaultOperators, Operators } from './render/operator'
 import { createTrie, Trie } from './util/operator-trie'
-import { timezoneOffset } from './util/strftime'
 
 export interface LiquidOptions {
   /** A directory or an array of directories from where to resolve layout and include templates, and the filename passed to `.renderFile()`. If it's an array, the files are looked up in the order they occur in the array. Defaults to `["."]` */
@@ -123,7 +122,6 @@ export const defaultOptions: NormalizedFullOptions = {
   lenientIf: false,
   globals: {},
   keepOutputType: false,
-  timezoneOffset: timezoneOffset,
   operators: defaultOperators,
   operatorsTrie: createTrie(defaultOperators)
 }

src/util/strftime.ts

@@ -1,7 +1,5 @@
 import { changeCase, padStart, padEnd } from './underscore'
 
-export const timezoneOffset = new Date().getTimezoneOffset()
-const ISO8601_TIMEZONE_PATTERN = /([zZ]|([+-])(\d{2}):(\d{2}))$/
 const rFormat = /%([-_0^#:]+)?(\d+)?([EO])?(.)/
 const monthNames = [
   'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August',
@@ -127,10 +125,10 @@ const formatCodes = {
   y: (d: Date) => d.getFullYear().toString().substring(2, 4),
   Y: (d: Date) => d.getFullYear(),
   z: (d: Date, opts: FormatOptions) => {
-    const nOffset = Math.abs(timezoneOffset)
+    const nOffset = Math.abs(d.getTimezoneOffset())
     const h = Math.floor(nOffset / 60)
     const m = nOffset % 60
-    return (timezoneOffset > 0 ? '-' : '+') +
+    return (d.getTimezoneOffset() > 0 ? '-' : '+') +
       padStart(h, 2, '0') +
       (opts.flags[':'] ? ':' : '') +
       padStart(m, 2, '0')
@@ -169,31 +167,3 @@ function format (d: Date, match: RegExpExecArray) {
   if (flags['-']) padWidth = 0
   return padStart(ret, padWidth, padChar)
 }
-
-/**
- * Create a Date object fixed to it's declared Timezone. Both
- * - 2021-08-06T02:29:00.000Z and
- * - 2021-08-06T02:29:00.000+08:00
- * will always be displayed as
- * - 2021-08-06 02:29:00
- * regardless timezoneOffset in JavaScript realm
- *
- * The implementation hack:
- * Instead of calling `.getMonth()`/`.getUTCMonth()` respect to `preserveTimezones`,
- * we create a different Date to trick strftime, it's both simpler and more performant.
- * Given that a template is expected to be parsed fewer times than rendered.
- */
-export function createDateFixedToTimezone (dateString: string) {
-  const m = dateString.match(ISO8601_TIMEZONE_PATTERN)
-  // representing a UTC datetime
-  if (m && m[1] === 'Z') {
-    return new Date(+new Date(dateString) + timezoneOffset * 60000)
-  }
-  // has a timezone specified
-  if (m && m[2] && m[3] && m[4]) {
-    const [, , sign, hours, minutes] = m
-    const delta = (sign === '+' ? 1 : -1) * (parseInt(hours, 10) * 60 + parseInt(minutes, 10))
-    return new Date(+new Date(dateString) + (timezoneOffset + delta) * 60000)
-  }
-  return new Date(dateString)
-}

src/util/timezone-date.ts

@@ -0,0 +1,53 @@
+// one minute in milliseconds
+const OneMinute = 60000
+const hostTimezoneOffset = new Date().getTimezoneOffset()
+const ISO8601_TIMEZONE_PATTERN = /([zZ]|([+-])(\d{2}):(\d{2}))$/
+
+/**
+ * A date implementation with timezone info, just like Ruby date
+ *
+ * Implementation:
+ * - create a Date offset by it's timezone difference, avoiding overriding a bunch of methods
+ * - rewrite getTimezoneOffset() to trick strftime
+ */
+export class TimezoneDate extends Date {
+  private timezoneOffset?: number
+  constructor (init: string | number | Date, timezoneOffset: number) {
+    if (init instanceof TimezoneDate) return init
+    const diff = (hostTimezoneOffset - timezoneOffset) * OneMinute
+    const time = new Date(init).getTime() + diff
+    super(time)
+    this.timezoneOffset = timezoneOffset
+  }
+  getTimezoneOffset () {
+    return this.timezoneOffset!
+  }
+
+  /**
+   * Create a Date object fixed to it's declared Timezone. Both
+   * - 2021-08-06T02:29:00.000Z and
+   * - 2021-08-06T02:29:00.000+08:00
+   * will always be displayed as
+   * - 2021-08-06 02:29:00
+   * regardless timezoneOffset in JavaScript realm
+   *
+   * The implementation hack:
+   * Instead of calling `.getMonth()`/`.getUTCMonth()` respect to `preserveTimezones`,
+   * we create a different Date to trick strftime, it's both simpler and more performant.
+   * Given that a template is expected to be parsed fewer times than rendered.
+   */
+  static createDateFixedToTimezone (dateString: string) {
+    const m = dateString.match(ISO8601_TIMEZONE_PATTERN)
+    // representing a UTC timestamp
+    if (m && m[1] === 'Z') {
+      return new TimezoneDate(+new Date(dateString), 0)
+    }
+    // has a timezone specified
+    if (m && m[2] && m[3] && m[4]) {
+      const [, , sign, hours, minutes] = m
+      const delta = (sign === '+' ? -1 : 1) * (parseInt(hours, 10) * 60 + parseInt(minutes, 10))
+      return new TimezoneDate(+new Date(dateString), delta)
+    }
+    return new Date(dateString)
+  }
+}