Promise for minixhr:

apps/remix-ide/src/app/compiler/compiler-sourceVerifier-fetchAndCompile.js

@@ -107,7 +107,7 @@ export default class FetchAndCompile extends Plugin {
       version: data.metadata.compiler.version,
       languageName: data.metadata.language,
       evmVersion: data.metadata.settings.evmVersion,
-      optimize: data.metadata.settings.optimizer.enabled,
+      optimize: data.metadata.settings.optimizer.enabled
     }
     try {
       setTimeout(_ => this.emit('compiling', settings), 0)

apps/remix-ide/src/app/compiler/compiler-utils.js

- const semver = require('semver')
+const semver = require('semver')
+const minixhr = require('minixhr')
 /* global Worker */
 
 export const baseURLBin = 'https://solc-bin.ethereum.org/bin'
 export const baseURLWasm = 'https://solc-bin.ethereum.org/wasm'
 
-export const pathToURL = []
+export const pathToURL = {}
 
+// retrieves the URL of the given compiler version
 export function urlFromVersion (version) {
   return `${pathToURL[version]}/${version}`
 }
@@ -15,45 +17,23 @@ export function urlFromVersion (version) {
  * checks a compiler whitelist, browser support and OS.
  */
 export function canUseWorker (selectedVersion) {
-  // Following restrictions should be deleted when Solidity will release fixed versions of compilers.
-  // See https://github.com/ethereum/remix-ide/issues/2461
-  /* const isChrome = !!window.chrome
-  const os = retrieveOS()
-  // define a whitelist for Linux
-  const linuxWL = ['0.4.26', '0.5.3', '0.5.4', '0.5.5']
-  const version = semver.coerce(selectedVersion)
-  // defining whitelist for chrome
-  let isFromWhiteList = false
-  switch (os) {
-    case 'Windows':
-      isFromWhiteList = semver.gt(version, '0.5.2') || version === '0.4.26'
-      break
-    case 'Linux':
-      isFromWhiteList = semver.gt(version, '0.5.13') || linuxWL.includes(version)
-      break
-    default :
-      isFromWhiteList = true
-  } */
   const version = semver.coerce(selectedVersion)
   const isNightly = selectedVersion.includes('nightly')
-  return browserSupportWorker() && 
-    (
+  return browserSupportWorker() && (
     semver.gt(version, '0.6.3') ||
-      semver.gt(version, '0.3.5') && !isNightly
+    semver.gt(version, '0.3.6') && !isNightly
   )
-    // && (!isChrome || (isChrome && isFromWhiteList))
 }
 
 function browserSupportWorker () {
   return document.location.protocol !== 'file:' && Worker !== undefined
 }
 
-/* function retrieveOS () {
-  let osName = 'Unknown OS'
-  if (navigator.platform.indexOf('Win') !== -1) {
-    osName = 'Windows'
-  } else if (navigator.platform.indexOf('Linux') !== -1) {
-    osName = 'Linux'
-  }
-  return osName
-} */
+// returns a promice for minixhr
+export function promisedMiniXhr (url) {
+  return new Promise((resolve, reject) => {
+    minixhr(url, (json, event) => {
+      resolve({ json, event })
+    })
+  })
+}

apps/remix-ide/src/app/tabs/compileTab/compilerContainer.js

 
 const yo = require('yo-yo')
-const minixhr = require('minixhr')
 const helper = require('../../../lib/helper')
 const addTooltip = require('../../ui/tooltip')
 const semver = require('semver')
 const modalDialogCustom = require('../../ui/modal-dialog-custom')
 const css = require('../styles/compile-tab-styles')
-import { canUseWorker, baseURLBin, baseURLWasm, urlFromVersion, pathToURL } from '../../compiler/compiler-utils'
+import { canUseWorker, baseURLBin, baseURLWasm, urlFromVersion, pathToURL, promisedMiniXhr } from '../../compiler/compiler-utils'
 
 class CompilerContainer {
 
@@ -414,61 +413,42 @@ class CompilerContainer {
     if (this._view.version) this._view.version.innerText = text
   }
 
-  // fetching both normal and wasm builds and creating an array [version, baseUrl]
-  fetchAllVersion (callback) {
-    let allVersions, selectedVersion, allVersionsWasm, urls
+  // fetching both normal and wasm builds and creating a [version, baseUrl] map
+  async fetchAllVersion (callback) {
+    let allVersions, selectedVersion, allVersionsWasm
     // fetch normal builds
-    minixhr(`${this.data.baseURLBin}/list.json`, (json, event) => {
-      // @TODO: optimise and cache results to improve app loading times #2461
-      if (event.type !== 'error') {
+    const binRes = await promisedMiniXhr(`${this.data.baseURLBin}/list.json`)
+    // fetch wasm builds
+    const wasmRes = await promisedMiniXhr(`${this.data.baseURLWasm}/list.json`)
+    if (binRes.event.type === 'error' && wasmRes.event.type === 'error') {
+      allVersions = [{ path: 'builtin', longVersion: 'latest local version' }]
+      selectedVersion = 'builtin'
+      callback(allVersions, selectedVersion)
+    }
     try {
-          const data = JSON.parse(json)
-          allVersions = data.builds.slice().reverse()
+      allVersions = JSON.parse(binRes.json).builds.slice().reverse()
       selectedVersion = this.data.defaultVersion
       if (this.queryParams.get().version) selectedVersion = this.queryParams.get().version
-          // no fetching wasm builds
-          minixhr(`${this.data.baseURLWasm}/list.json`, (json, event) => {
-            // @TODO: optimise and cache results to improve app loading times #2461
-            if (event.type !== 'error') {
-              try {
-                const data = JSON.parse(json)
-                allVersionsWasm = data.builds.slice().reverse()
-                //selectedVersion = this.data.defaultVersion
-                if (this.queryParams.get().version) selectedVersion = this.queryParams.get().version
-                // rewriting all versions in allVersions which exist in allVersionsWasm
-                if (allVersionsWasm && allVersions)
-                allVersions.forEach((compiler, index) => {
-                  const rewritten = allVersionsWasm.findIndex(oldCompiler => { return oldCompiler.longVersion === compiler.longVersion })
-                  if (-1 !== rewritten) {
-                    allVersions[index] = allVersionsWasm[rewritten]
-                    pathToURL[compiler.path] = baseURLWasm
-                  } else {
-                    pathToURL[compiler.path] = baseURLBin
+      if (wasmRes.event.type !== 'error') {
+        allVersionsWasm = JSON.parse(wasmRes.json).builds.slice().reverse()
       }
-                })
-                callback(allVersions, selectedVersion)
     } catch (e) {
-                addTooltip('Cannot load compiler version list. It might have been blocked by an advertisement blocker. Please try deactivating any of them from this page and reload.')
+      addTooltip('Cannot load compiler version list. It might have been blocked by an advertisement blocker. Please try deactivating any of them from this page and reload. Error: ' + e)
     }
+    // replace in allVersions those compiler builds which exist in allVersionsWasm with new once
+    if (allVersionsWasm && allVersions) {
+      allVersions.forEach((compiler, index) => {
+        const wasmIndex = allVersionsWasm.findIndex(wasmCompiler => { return wasmCompiler.longVersion === compiler.longVersion })
+        if (wasmIndex !== -1) {
+          allVersions[index] = allVersionsWasm[wasmIndex]
+          pathToURL[compiler.path] = baseURLWasm
         } else {
-              allVersionsWasm = [{ path: 'builtin', longVersion: 'latest local version' }]
-              selectedVersion = 'builtin'
+          pathToURL[compiler.path] = baseURLBin
         }
-            //callback(allVersions, selectedVersion)
       })
-        } catch (e) {
-          addTooltip('Cannot load compiler version list. It might have been blocked by an advertisement blocker. Please try deactivating any of them from this page and reload.')
     }
-      } else {
-        allVersions = [{ path: 'builtin', longVersion: 'latest local version' }]
-        selectedVersion = 'builtin'
-      }
-      //callback(allVersions, selectedVersion)
-    })
-    
-    
+    callback(allVersions, selectedVersion)
   }
-
   scheduleCompilation () {
     if (!this.config.get('autoCompile')) return
     if (this.data.compileTimeout) window.clearTimeout(this.data.compileTimeout)