Better function and class instance print

denoland · Jun 7, 2018 · 4ff0521 · 4ff0521
1 parent 70457c2
commit 4ff0521
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Showing 2 changed files with 57 additions and 8 deletions.
diff --git a/console.ts b/console.ts
@@ -1,6 +1,17 @@
 // tslint:disable-next-line:no-any
 type ConsoleContext = Set<any>;
 
+// tslint:disable-next-line:no-any
+function getClassInstanceName(instance: any): string {
+  if (typeof instance !== "object") {
+    return "";
+  }
+  if (instance && instance.__proto__ && instance.__proto__.constructor) {
+    return instance.__proto__.constructor.name; // could be "Object" or "Array"
+  }
+  return "";
+}
+
 // tslint:disable-next-line:no-any
 function stringify(ctx: ConsoleContext, value: any): string {
   switch (typeof value) {
@@ -9,8 +20,12 @@ function stringify(ctx: ConsoleContext, value: any): string {
     case "number":
     case "boolean":
     case "undefined":
+    case "symbol":
       return String(value);
     case "function":
+      if (value.name && value.name !== "anonymous") { // from MDN spec
+        return `[Function: ${value.name}]`;
+      }
       return "[Function]";
     case "object":
       if (value === null) {
@@ -22,30 +37,51 @@ function stringify(ctx: ConsoleContext, value: any): string {
       }
 
       ctx.add(value);
-      const valStrings = [];
+      let entries: string[] = [];
 
       if (Array.isArray(value)) {
         for (const el of value) {
-          valStrings.push(stringify(ctx, el));
+          entries.push(stringify(ctx, el));
         }
 
         ctx.delete(value);
 
-        if (valStrings.length === 0) {
+        if (entries.length === 0) {
           return "[]";
         }
-        return `[ ${valStrings.join(", ")} ]`;
+        return `[ ${entries.join(", ")} ]`;
       } else {
+        let baseString = "";
+
+        const className = getClassInstanceName(value);
+        let shouldShowClassName = false;
+        if (className && className !== "Object" && className !== "anonymous") {
+          shouldShowClassName = true;
+        }
+
         for (const key of Object.keys(value)) {
-          valStrings.push(`${key}: ${stringify(ctx, value[key])}`);
+          const keyVal = value[key];
+          // do not show methods of class instance
+          if (!shouldShowClassName || typeof keyVal !== "function") {
+            entries.push(`${key}: ${stringify(ctx, value[key])}`);
+          }
         }
 
+        entries = entries.filter(e => !!e); // remove empty entries
+
         ctx.delete(value);
 
-        if (valStrings.length === 0) {
-          return "{}";
+        if (entries.length === 0) {
+          baseString = "{}";
+        } else {
+          baseString = `{ ${entries.join(", ")} }`;
         }
-        return `{ ${valStrings.join(", ")} }`;
+
+        if (shouldShowClassName) {
+          baseString = `${className} ${baseString}`;
+        }
+
+        return baseString;
       }
     default:
       return "[Not Implemented]";

diff --git a/tests.ts b/tests.ts
@@ -69,6 +69,16 @@ test(function tests_console_assert() {
 });
 
 test(function tests_console_stringify_circular() {
+  class Base {
+    a = 1;
+    m1() {}
+  }
+
+  class Extended extends Base {
+    b = 2;
+    m2() {}
+  }
+
   // tslint:disable-next-line:no-any
   const nestedObj: any = {
     num: 1,
@@ -77,6 +87,8 @@ test(function tests_console_stringify_circular() {
     method() {},
     un: undefined,
     nu: null,
+    arrowFunc: () => {},
+    extendedClass: new Extended(),
   };
 
   const circularObj = {
@@ -89,6 +101,7 @@ test(function tests_console_stringify_circular() {
     nested: nestedObj,
     emptyObj: {},
     arr: [1, "s", false, null, nestedObj],
+    baseClass: new Base(),
   };
 
   nestedObj.o = circularObj;