Skip to content

Utils.md

Latest commit

 

History

History
104 lines (69 loc) · 3.58 KB

Utils.md

File metadata and controls

104 lines (69 loc) · 3.58 KB
Raw

Utils

copy

copy (dest, ...sources)

Copies all enumerable properties from each of the given sources. Returns the dest object.

copyOwnExcept

copy (dest, src, exceptRe)

Copies all enumerable, own properties from src to dest and returns the dest object. Properties that match exceptRe are skipped.

inspect

inspect (object, options)

Returns a human-readable string form of the object (similar to JSON but nicer).

Valid options are:

  • showHidden (false) If true, the object's non-enumerable symbols and properties will be included in the formatted result.
  • depth (2) Specifies the number of times to recurse while formatting the object. This is useful for inspecting large complicated objects. To make it recurse indefinitely pass null.
  • colors (false) If true, the output will be styled with ANSI color codes. Colors are customizable, see Customizing util.inspect colors.
  • customInspect (true) If false, then custom inspect(depth, opts) functions exported on the object being inspected will not be called.
  • showProxy (false) If true, then objects and functions that are Proxy objects will be introspected to show their target and handler objects.
  • maxArrayLength (100) Specifies the maximum number of array and TypedArray elements to include when formatting. Set to null to show all array elements. Set to 0 or negative to show no array elements.
  • breakLength (60) The length at which an object's keys are split across multiple lines. Set to Infinity to format an object as a single line.

When running on Node.js, this method is assigned to the util module's version. For browsers, this method is an extracted version of Node.js's inspect method.

Note: At present showProxy is not supported in the browser because it relies on direct access to the JavaScript engine.

isArrayLike

isArrayLike (value)

Returns true if the value has a length property and should be treated like an Array. For example, an arguments object.

isEqual

isEqual (value1, value2, strict)

Recursively compares two values for equality (==) or strict equality (===). If the values are both arrays or objects, their contents are compared. In other words, when strict is true this method does not compare object references but rather contents.

Objects are considered equal if they have the same prototype and keys (regardless of order) and values for each key passes the same isEqual test.

Arrays are considered equal if they have the same number of elements and those elements pass the same isEqual test.

isPromise

isPromise (...values)

Returns true if any of the values are promises (have then methods).

toArray

toArray (value)

If value is an array, it is returned. If it isArrayLike it is converted to a true array (its elements are shallow copied).

Otherwise, this method returns an empty array if value is null or undefined, or an array with the value.

typeOf

typeOf (value)

This is an enhanced typeof replacement. It returns the same results for these types:

  • boolean
  • function
  • number
  • string
  • undefined

Otherwise, it returns strings derived from Object.prototype.toString (and caches them) such as these:

  • array
  • arguments
  • date
  • error
  • regexp
  • null

More specifically, if the string returned by Object.prototype.toString matches the typical "[object Foo]" format, the "Foo" is extracted and toLowerCase() is applied for the result. Otherwise, the text from Object.prototype.toString is returned.