Lots of ESLint fixes

GoogleChromeLabs · Nov 24, 2018 · 5d0af3d · 5d0af3d
1 parent 6571ff0
commit 5d0af3d
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Showing 6 changed files with 132 additions and 86 deletions.
diff --git a/.eslintrc.js b/.eslintrc.js
@@ -0,0 +1,35 @@
+module.exports = {
+    env: {
+        browser: true,
+        es6: true
+    },
+    parserOptions: {
+        sourceType: 'module',
+    },
+    extends: 'google',
+    rules: {
+        'max-len': ['warn',
+            {
+                code: 130
+            } // 130 on GitHub, 80 on npmjs.org for README.md code blocks
+        ],
+        'arrow-parens': ['error', 'as-needed'],
+        'space-before-function-paren': [
+            'error',
+            {
+                anonymous: 'always',
+                named: 'never'
+            }
+        ],
+        'no-negated-condition': 'warn',
+        'spaced-comment': ['error', 'always',
+            {
+                exceptions: ['/']
+            }
+        ]
+    },
+    globals: {
+        DOMException: false,
+        URL: false,
+    }
+};
diff --git a/package.json b/package.json
@@ -2,22 +2,22 @@
   "name": "quicklink",
   "version": "0.0.1",
   "description": "Faster page-loads by prefetching links during idle time",
-  "main": "src/index.mjs",
+  "main": "dist/quicklink.js",
   "repository": "https://github.com/addyosmani/quicklink.git",
   "author": "addyosmani <[email protected]>",
   "license": "Apache-2.0",
   "private": false,
-  "main": "dist/quicklink.js",
   "module": "dist/quicklink.mjs",
   "jsnext:main": "dist/quicklink.mjs",
   "umd:main": "dist/quicklink.umd.js",
   "scripts": {
-    "test": "eslint src",
+    "lint": "eslint src/*.mjs",
     "build": "microbundle src/index.mjs --no-sourcemap",
     "prepare": "npm run -s build"
   },
   "devDependencies": {
     "eslint": "^5.9.0",
+    "eslint-config-google": "^0.11.0",
     "microbundle": "^0.7.0"
   }
 }
diff --git a/src/index.mjs b/src/index.mjs
@@ -2,68 +2,75 @@ import prefetch from './prefetch.mjs';
 import requestIdleCallback from './request-idle-callback.mjs';
 
 /**
- * 
- * @param urls Array of URLs to prefetch
+ * Prefetch an array of URLs using rel=prefetch
+ * if supported. Falls back to XHR otherwise.
+ * @param {Array} urls Array of URLs to prefetch
  */
 function fetchLinks(urls) {
-    urls.forEach((url) => {
-        prefetch(url);
-    });
+  urls.forEach(url => {
+    prefetch(url);
+  });
 }
 
 /**
- * Extract only links that are in the visible viewport
- * @param el DOM element to check for in-viewport links
+ * Extract links from a provided DOM element that are
+ * in the user's viewport.
+ * @param {Object} el DOM element to check for in-viewport links
+ * @return {Promise} resolving with list of URLs found
  */
 function extractInViewportLinks(el) {
-    return new Promise((resolve, reject) => {
-        const urls = [];
-        const links = el.querySelectorAll('a');
-        const observer = new IntersectionObserver(entries => {
-            entries.forEach(entry => {
-                // Link is in the view
-                if (entry.intersectionRatio > 0) {
-                    urls.push(entry.target.href);
-                } else {
-                    // Link is out of the view
-                }
-            });
-            resolve(urls);
-        });
-        links.forEach(link => {
-            observer.observe(link);
-        });
+  return new Promise((resolve, reject) => {
+    const urls = [];
+    const links = el.querySelectorAll('a');
+    const observer = new IntersectionObserver(entries => {
+      entries.forEach(entry => {
+        // Link is in the view
+        if (entry.intersectionRatio > 0) {
+          urls.push(entry.target.href);
+        } else {
+          // Link is out of the view
+        }
+      });
+      resolve(urls);
     });
+    links.forEach(link => {
+      observer.observe(link);
+    });
+  });
 }
 
 /**
- * 
- * @param options 
+ * Prefetch an array of URLs if the user's effective
+ * connection type and data-saver preferences suggests
+ * it would be useful. By default, looks at in-viewport
+ * links for `document`. Can also work off a supplied
+ * DOM element or static array of URLs.
+ * @param {Object} options supported options
  * options.urls: Array of URLs to prefetch (override)
  * options.el: DOM element to prefetch in-viewport links of
  */
-export default function quicklink(options) {
-    options = options || {};
-    requestIdleCallback(() => {
-        if ('connection' in navigator) {
-            // Don't prefetch if the user is on 2G..
-            if (navigator.connection.effectiveType && /\slow-2g|2g/.test(navigator.connection.effectiveType)) {
-                return;
-            }
-            // Don't prefetch if Save-Data is enabled..
-            if (navigator.connection.saveData) {
-                return;
-            }
-        }
-        // Prefetch an array of URLs if supplied (as an override)
-        if (options.urls !== undefined && options.urls.length > 0) {
-            fetchLinks(options.urls);
-        } else {
-            // Element to extract in-viewport links for
-            let el = options.el || document;
-            extractInViewportLinks(el).then((urls) => {
-                fetchLinks(urls);
-            });
-        }
-    });
-}
+export default function (options) {
+  options = options || {};
+  requestIdleCallback(() => {
+    if ('connection' in navigator) {
+      // Don't prefetch if the user is on 2G..
+      if (navigator.connection.effectiveType && /\slow-2g|2g/.test(navigator.connection.effectiveType)) {
+        return;
+      }
+      // Don't prefetch if Save-Data is enabled..
+      if (navigator.connection.saveData) {
+        return;
+      }
+    }
+    // Prefetch an array of URLs if supplied (as an override)
+    if (options.urls !== undefined && options.urls.length > 0) {
+      fetchLinks(options.urls);
+    } else {
+      // Element to extract in-viewport links for
+      const el = options.el || document;
+      extractInViewportLinks(el).then(urls => {
+        fetchLinks(urls);
+      });
+    }
+  });
+}
diff --git a/src/prefetch.mjs b/src/prefetch.mjs
@@ -1,47 +1,47 @@
-const support = function(feature) {
+const support = function (feature) {
   if (typeof document === `undefined`) {
-    return false
+    return false;
   }
-  const fakeLink = document.createElement(`link`)
+  const fakeLink = document.createElement(`link`);
   try {
     if (fakeLink.relList && typeof fakeLink.relList.supports === `function`) {
-      return fakeLink.relList.supports(feature)
+      return fakeLink.relList.supports(feature);
     }
   } catch (err) {
-    return false
+    return false;
   }
-}
-const linkPrefetchStrategy = function(url) {
+};
+const linkPrefetchStrategy = function (url) {
   if (typeof document === `undefined`) {
-    return
+    return;
   }
-  const link = document.createElement(`link`)
-  link.setAttribute(`rel`, `prefetch`)
-  link.setAttribute(`href`, url)
+  const link = document.createElement(`link`);
+  link.setAttribute(`rel`, `prefetch`);
+  link.setAttribute(`href`, url);
   const parentElement =
     document.getElementsByTagName(`head`)[0] ||
-    document.getElementsByName(`script`)[0].parentNode
-  parentElement.appendChild(link)
-}
-const xhrPrefetchStrategy = function(url) {
-  const req = new XMLHttpRequest()
-  req.open(`GET`, url, true)
-  req.withCredentials = true
-  req.send(null)
-}
+    document.getElementsByName(`script`)[0].parentNode;
+  parentElement.appendChild(link);
+};
+const xhrPrefetchStrategy = function (url) {
+  const req = new XMLHttpRequest();
+  req.open(`GET`, url, true);
+  req.withCredentials = true;
+  req.send(null);
+};
 
 const supportedPrefetchStrategy = support(`prefetch`)
   ? linkPrefetchStrategy
-  : xhrPrefetchStrategy
+  : xhrPrefetchStrategy;
 
-const preFetched = {}
+const preFetched = {};
 
-const prefetch = function(url) {
+const prefetch = function (url) {
   if (preFetched[url]) {
-    return
+    return;
   }
-  preFetched[url] = true
-  supportedPrefetchStrategy(url)
-}
+  preFetched[url] = true;
+  supportedPrefetchStrategy(url);
+};
 
-export default prefetch
+export default prefetch;
diff --git a/src/request-idle-callback.mjs b/src/request-idle-callback.mjs
@@ -1,15 +1,15 @@
 // RIC and shim for browsers setTimeout() without it
 const requestIdleCallback = window.requestIdleCallback ||
   function (cb) {
-    let start = Date.now();
+    const start = Date.now();
     return setTimeout(function () {
       cb({
         didTimeout: false,
         timeRemaining: function () {
           return Math.max(0, 50 - (Date.now() - start));
-        }
+        },
       });
     }, 1);
-  }
+  };
 
-export default requestIdleCallback;
+export default requestIdleCallback;
diff --git a/yarn.lock b/yarn.lock
@@ -809,6 +809,10 @@ escape-string-regexp@^1.0.2, escape-string-regexp@^1.0.5:
   version "1.0.5"
   resolved "https://registry.yarnpkg.com/escape-string-regexp/-/escape-string-regexp-1.0.5.tgz#1b61c0562190a8dff6ae3bb2cf0200ca130b86d4"
 
+eslint-config-google@^0.11.0:
+  version "0.11.0"
+  resolved "https://registry.yarnpkg.com/eslint-config-google/-/eslint-config-google-0.11.0.tgz#fd0fc70be2e9114df097cac93a9b5b0d4e1c6830"
+
 eslint-scope@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/eslint-scope/-/eslint-scope-4.0.0.tgz#50bf3071e9338bcdc43331794a0cb533f0136172"