Merge pull request #2226 from levithomason/feature/notify-on-finish

Notify when less.js is done processing

Author: lukeapage

lib/less-browser/index.js

@@ -26,6 +26,7 @@ require("./log-listener")(less, options);
 var errors = require("./error-reporting")(window, less, options);
 var browser = require("./browser");
 var cache = options.cache || require("./cache")(window, options, less.logger);
+var PromiseConstructor = typeof Promise === 'undefined' ? require('promise') : Promise;
 
 options.env = options.env || (window.location.hostname == '127.0.0.1' ||
                               window.location.hostname == '0.0.0.0'   ||
@@ -238,33 +239,45 @@ for (var i = 0; i < links.length; i++) {
 // CSS without reloading less-files
 //
 less.modifyVars = function(record) {
-    less.refresh(false, record);
+    return less.refresh(false, record);
 };
 
 less.refresh = function (reload, modifyVars) {
-    var startTime, endTime;
-    startTime = endTime = new Date();
-
-    loadStyleSheets(function (e, css, _, sheet, webInfo) {
-        if (e) {
-            return errors.add(e, e.href || sheet.href);
-        }
-        if (webInfo.local) {
-            less.logger.info("loading " + sheet.href + " from cache.");
-        } else {
-            less.logger.info("rendered " + sheet.href + " successfully.");
-            css = postProcessCSS(css);
-            browser.createCSS(window.document, css, sheet);
-            cache.setCSS(sheet.href, webInfo.lastModified, css);
-        }
-        less.logger.info("css for " + sheet.href + " generated in " + (new Date() - endTime) + 'ms');
-        if (webInfo.remaining === 0) {
-            less.logger.info("less has finished. css generated in " + (new Date() - startTime) + 'ms');
-        }
-        endTime = new Date();
-    }, reload, modifyVars);
+    less.hasFinished = new PromiseConstructor(function (resolve, reject) {
+        var startTime, endTime, totalMilliseconds;
+        startTime = endTime = new Date();
+
+        loadStyleSheets(function (e, css, _, sheet, webInfo) {
+            if (e) {
+                errors.add(e, e.href || sheet.href);
+                reject(e);
+            }
+            if (webInfo.local) {
+                less.logger.info("loading " + sheet.href + " from cache.");
+            } else {
+                less.logger.info("rendered " + sheet.href + " successfully.");
+                css = postProcessCSS(css);
+                browser.createCSS(window.document, css, sheet);
+                cache.setCSS(sheet.href, webInfo.lastModified, css);
+            }
+            less.logger.info("css for " + sheet.href + " generated in " + (new Date() - endTime) + 'ms');
+            if (webInfo.remaining === 0) {
+                totalMilliseconds = new Date() - startTime;
+                less.logger.info("less has finished. css generated in " + totalMilliseconds + 'ms');
+                resolve({
+                    startTime: startTime,
+                    endTime: endTime,
+                    totalMilliseconds: totalMilliseconds,
+                    sheets: less.sheets.length
+                });
+            }
+            endTime = new Date();
+        }, reload, modifyVars);
+    
+        loadStyles(modifyVars);
+    });
 
-    loadStyles(modifyVars);
+    return less.hasFinished;
 };
 
 less.refreshStyles = loadStyles;