Migrate scrape-examples.js to ES6

Author: GuillaumeGomez

src/librustdoc/html/static/js/scrape-examples.js

@@ -1,24 +1,27 @@
-/* global addClass, hasClass, removeClass, onEach */
+/* eslint-env es6 */
+/* eslint no-var: "error" */
+/* eslint prefer-const: "error" */
+/* global addClass, hasClass, removeClass, onEachLazy */
 
 (function () {
     // Number of lines shown when code viewer is not expanded
     const MAX_LINES = 10;
 
     // Scroll code block to the given code location
     function scrollToLoc(elt, loc) {
-        var lines = elt.querySelector('.line-numbers');
-        var scrollOffset;
+        const lines = elt.querySelector('.line-numbers');
+        let scrollOffset;
 
         // If the block is greater than the size of the viewer,
         // then scroll to the top of the block. Otherwise scroll
         // to the middle of the block.
         if (loc[1] - loc[0] > MAX_LINES) {
-            var line = Math.max(0, loc[0] - 1);
+            const line = Math.max(0, loc[0] - 1);
             scrollOffset = lines.children[line].offsetTop;
         } else {
-            var wrapper = elt.querySelector(".code-wrapper");
-            var halfHeight = wrapper.offsetHeight / 2;
-            var offsetMid = (lines.children[loc[0]].offsetTop
+            const wrapper = elt.querySelector(".code-wrapper");
+            const halfHeight = wrapper.offsetHeight / 2;
+            const offsetMid = (lines.children[loc[0]].offsetTop
                              + lines.children[loc[1]].offsetTop) / 2;
             scrollOffset = offsetMid - halfHeight;
         }
@@ -28,21 +31,21 @@
     }
 
     function updateScrapedExample(example) {
-        var locs = JSON.parse(example.attributes.getNamedItem("data-locs").textContent);
-        var locIndex = 0;
-        var highlights = example.querySelectorAll('.highlight');
-        var link = example.querySelector('.scraped-example-title a');
+        const locs = JSON.parse(example.attributes.getNamedItem("data-locs").textContent);
+        let locIndex = 0;
+        const highlights = Array.prototype.slice.call(example.querySelectorAll('.highlight'));
+        const link = example.querySelector('.scraped-example-title a');
 
         if (locs.length > 1) {
             // Toggle through list of examples in a given file
-            var onChangeLoc = function(changeIndex) {
+            const onChangeLoc = function(changeIndex) {
                 removeClass(highlights[locIndex], 'focus');
                 changeIndex();
                 scrollToLoc(example, locs[locIndex][0]);
                 addClass(highlights[locIndex], 'focus');
 
-                var url = locs[locIndex][1];
-                var title = locs[locIndex][2];
+                const url = locs[locIndex][1];
+                const title = locs[locIndex][2];
 
                 link.href = url;
                 link.innerHTML = title;
@@ -63,7 +66,7 @@
                 });
         }
 
-        var expandButton = example.querySelector('.expand');
+        const expandButton = example.querySelector('.expand');
         if (expandButton) {
             expandButton.addEventListener('click', function () {
                 if (hasClass(example, "expanded")) {
@@ -79,24 +82,24 @@
         scrollToLoc(example, locs[0][0]);
     }
 
-    var firstExamples = document.querySelectorAll('.scraped-example-list > .scraped-example');
-    onEach(firstExamples, updateScrapedExample);
-    onEach(document.querySelectorAll('.more-examples-toggle'), function(toggle) {
+    const firstExamples = document.querySelectorAll('.scraped-example-list > .scraped-example');
+    onEachLazy(firstExamples, updateScrapedExample);
+    onEachLazy(document.querySelectorAll('.more-examples-toggle'), function(toggle) {
         // Allow users to click the left border of the <details> section to close it,
         // since the section can be large and finding the [+] button is annoying.
-        toggle.querySelectorAll('.toggle-line, .hide-more').forEach(button => {
+        onEachLazy(toggle.querySelectorAll('.toggle-line, .hide-more'), button => {
             button.addEventListener('click', function() {
                 toggle.open = false;
             });
         });
 
-        var moreExamples = toggle.querySelectorAll('.scraped-example');
+        const moreExamples = toggle.querySelectorAll('.scraped-example');
         toggle.querySelector('summary').addEventListener('click', function() {
             // Wrapping in setTimeout ensures the update happens after the elements are actually
             // visible. This is necessary since updateScrapedExample calls scrollToLoc which
             // depends on offsetHeight, a property that requires an element to be visible to
             // compute correctly.
-            setTimeout(function() { onEach(moreExamples, updateScrapedExample); });
+            setTimeout(function() { onEachLazy(moreExamples, updateScrapedExample); });
         }, {once: true});
     });
 })();