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Added node.util.md

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+# util
+
+ Stability: 5 - Locked
+
+These functions are in the module `'util'`. Use `require('util')` to access
+them.
+
+
+## util.format(format, [...])
+
+Returns a formatted string using the first argument as a `printf`-like format.
+
+The first argument is a string that contains zero or more *placeholders*.
+Each placeholder is replaced with the converted value from its corresponding
+argument. Supported placeholders are:
+
+* `%s` - String.
+* `%d` - Number (both integer and float).
+* `%j` - JSON.
+* `%%` - single percent sign (`'%'`). This does not consume an argument.
+
+If the placeholder does not have a corresponding argument, the placeholder is
+not replaced.
+
+ util.format('%s:%s', 'foo'); // 'foo:%s'
+
+If there are more arguments than placeholders, the extra arguments are
+converted to strings with `util.inspect()` and these strings are concatenated,
+delimited by a space.
+
+ util.format('%s:%s', 'foo', 'bar', 'baz'); // 'foo:bar baz'
+
+If the first argument is not a format string then `util.format()` returns
+a string that is the concatenation of all its arguments separated by spaces.
+Each argument is converted to a string with `util.inspect()`.
+
+ util.format(1, 2, 3); // '1 2 3'
+
+
+## util.debug(string)
+
+A synchronous output function. Will block the process and
+output `string` immediately to `stderr`.
+
+ require('util').debug('message on stderr');
+
+## util.error([...])
+
+Same as `util.debug()` except this will output all arguments immediately to
+`stderr`.
+
+## util.puts([...])
+
+A synchronous output function. Will block the process and output all arguments
+to `stdout` with newlines after each argument.
+
+## util.print([...])
+
+A synchronous output function. Will block the process, cast each argument to a
+string then output to `stdout`. Does not place newlines after each argument.
+
+## util.log(string)
+
+Output with timestamp on `stdout`.
+
+ require('util').log('Timestamped message.');
+
+
+## util.inspect(object, [showHidden], [depth], [colors])
+
+Return a string representation of `object`, which is useful for debugging.
+
+If `showHidden` is `true`, then the object's non-enumerable properties will be
+shown too. Defaults to `false`.
+
+If `depth` is provided, it tells `inspect` how many times to recurse while
+formatting the object. This is useful for inspecting large complicated objects.
+
+The default is to only recurse twice. To make it recurse indefinitely, pass
+in `null` for `depth`.
+
+If `colors` is `true`, the output will be styled with ANSI color codes.
+Defaults to `false`.
+
+Example of inspecting all properties of the `util` object:
+
+ var util = require('util');
+
+ console.log(util.inspect(util, true, null));
+
+
+## util.isArray(object)
+
+Returns `true` if the given "object" is an `Array`. `false` otherwise.
+
+ var util = require('util');
+
+ util.isArray([])
+ // true
+ util.isArray(new Array)
+ // true
+ util.isArray({})
+ // false
+
+
+## util.isRegExp(object)
+
+Returns `true` if the given "object" is a `RegExp`. `false` otherwise.
+
+ var util = require('util');
+
+ util.isRegExp(/some regexp/)
+ // true
+ util.isRegExp(new RegExp('another regexp'))
+ // true
+ util.isRegExp({})
+ // false
+
+
+## util.isDate(object)
+
+Returns `true` if the given "object" is a `Date`. `false` otherwise.
+
+ var util = require('util');
+
+ util.isDate(new Date())
+ // true
+ util.isDate(Date())
+ // false (without 'new' returns a String)
+ util.isDate({})
+ // false
+
+
+## util.isError(object)
+
+Returns `true` if the given "object" is an `Error`. `false` otherwise.
+
+ var util = require('util');
+
+ util.isError(new Error())
+ // true
+ util.isError(new TypeError())
+ // true
+ util.isError({ name: 'Error', message: 'an error occurred' })
+ // false
+
+
+## util.pump(readableStream, writableStream, [callback])
+
+Experimental
+
+Read the data from `readableStream` and send it to the `writableStream`.
+When `writableStream.write(data)` returns `false` `readableStream` will be
+paused until the `drain` event occurs on the `writableStream`. `callback` gets
+an error as its only argument and is called when `writableStream` is closed or
+when an error occurs.
+
+
+## util.inherits(constructor, superConstructor)
+
+Inherit the prototype methods from one
+[constructor](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/constructor)
+into another. The prototype of `constructor` will be set to a new
+object created from `superConstructor`.
+
+As an additional convenience, `superConstructor` will be accessible
+through the `constructor.super_` property.
+
+ var util = require("util");
+ var events = require("events");
+
+ function MyStream() {
+ events.EventEmitter.call(this);
+ }
+
+ util.inherits(MyStream, events.EventEmitter);
+
+ MyStream.prototype.write = function(data) {
+ this.emit("data", data);
+ }
+
+ var stream = new MyStream();
+
+ console.log(stream instanceof events.EventEmitter); // true
+ console.log(MyStream.super_ === events.EventEmitter); // true
+
+ stream.on("data", function(data) {
+ console.log('Received data: "' + data + '"');
+ })
+ stream.write("It works!"); // Received data: "It works!"
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