Expose deno.inspect (#1378)

js/console.ts

@@ -474,3 +474,26 @@ export class Console {
     this.info(`${label}: ${duration}ms`);
   };
 }
+
+/**
+ * inspect() converts input into string that has the same format
+ * as printed by console.log(...);
+ */
+export function inspect(
+  value: any, // tslint:disable-line:no-any
+  options?: ConsoleOptions
+) {
+  const opts = options || {};
+  if (typeof value === "string") {
+    return value;
+  } else {
+    return stringify(
+      value,
+      // tslint:disable-next-line:no-any
+      new Set<any>(),
+      0,
+      // tslint:disable-next-line:triple-equals
+      opts.depth != undefined ? opts.depth : DEFAULT_MAX_DEPTH
+    );
+  }
+}

js/console_test.ts

@@ -1,6 +1,6 @@
 // Copyright 2018 the Deno authors. All rights reserved. MIT license.
 import { test, assert, assertEqual } from "./test_util.ts";
-import { stringifyArgs } from "./console.ts";
+import { stringifyArgs, inspect } from "./console.ts";
 
 import { Console } from "./console.ts";
 import { libdeno } from "./libdeno";
@@ -120,6 +120,8 @@ test(function consoleTestStringifyCircular() {
     // tslint:disable-next-line:max-line-length
     "Console { printFunc: [Function], log: [Function], debug: [Function], info: [Function], dir: [Function], warn: [Function], error: [Function], assert: [Function], count: [Function], countReset: [Function], time: [Function], timeLog: [Function], timeEnd: [Function] }"
   );
+  // test inspect is working the same
+  assertEqual(inspect(nestedObj), nestedObjExpected);
 });
 
 test(function consoleTestStringifyWithDepth() {
@@ -138,6 +140,11 @@ test(function consoleTestStringifyWithDepth() {
     stringifyArgs([nestedObj], { depth: null }),
     "{ a: { b: { c: { d: [Object] } } } }"
   );
+  // test inspect is working the same way
+  assertEqual(
+    inspect(nestedObj, { depth: 4 }),
+    "{ a: { b: { c: { d: [Object] } } } }"
+  );
 });
 
 test(function consoleTestCallToStringOnLabel() {

js/deno.ts

@@ -52,6 +52,7 @@ export { connect, dial, listen, Listener, Conn } from "./net";
 export { metrics } from "./metrics";
 export { resources } from "./resources";
 export { run, RunOptions, Process, ProcessStatus } from "./process";
+export { inspect } from "./console";
 export const args: string[] = [];
 
 // Provide the compiler API in an obfuscated way