ES6 Chapter 6 API Additions # Other API

Note: 5 primitive type (1) Undefined, (2)Null(Object), (3)Boolean (4)Number, (5)String

3.Math
- (1) Trigonometry:
  - cosh(..) - hyperbolic cosine
  - acosh(..) - hyperbolic arccosine
  - sinh(..) - hyperbolic sine
  - asinh(..) - hyperbolic arcsine
  - tanh(..) - hyperbolic tangent
  - atanh(..) - hyperbolic arctangent
  - hypot(..) - the squareroot of the sum of the squares
- (2) Arithmetic:
  - cbrt(..) - cube root
  - clz32(..) - count leading zeros in 32-bit binary representation
  - expm1(..) - the same as exp(x) - 1
  - log2(..) - binary logarithm (log base 2)
  - log10(..) - log base 10
  - log1p(..) - the same as log(x + 1)
  - imul(..) - 32-bit integer multiplication of two numbers
- (3) Meta:
  - sign(..) - returns the sign of the number
  - trunc(..) - returns only the integer part of a number
  - fround(..) - rounds to nearest 32-bit (single precision) floating point value

4.Number

(1) Static Properties
- Number.EPSILON - the minimum value between any two numbers: 2^-52
- Number.MAX_SAFE_INTEGER - The highest integer that can “safely” be represented unambiguously in a JS number value: 2^53
- Number.MIN_SAFE_INTEGER - The lowest integer that can “safely” be represented unambiguously in a JS number value: -(2^53 - 1) or (-2)^53 + 1 .
(2) [Static Function] Number.isNaN(..)
- [Background] The standard global isNaN(..) has been broken, it coerces the argument to a number type.
- [Purpose] ES6 adds a fixed utility Number.isNaN(..)
(3) [Static Function] Number.isFinite(..)
- [Background] The standard global isFinite(..) coerces its argument
- [Behavior] but Number.isFinite(..) omits the coercive behavior
- [Coercion] use Number.isFinite(+x) , which explicitly coerces x to a number before passing it in

(4) [Static Functions] Integer-related

      ==============(2) Number.isNaN============================
      var a = NaN, b = "NaN", c = 42;
      isNaN( a );// true
      isNaN( b );// true -- oops!
      isNaN( c );// false

      Number.isNaN( a );// true
      Number.isNaN( b );// false -- fixed!
      Number.isNaN( c );// false

      ================(3) Number.isFinite(..)======================
      var a = NaN, b = Infinity, c = 42;
      Number.isFinite( a ); // false
      Number.isFinite( b ); // false
      Number.isFinite( c ); // true

      var a = "42";
      isFinite( a );			// true
      Number.isFinite( a );	// false

      ================(4) Integer-related ================
      Number.isInteger( 4 ); 			// true
      Number.isInteger( 4.2 ); 		// false
      Number.isInteger( NaN );		// false
      Number.isInteger( Infinity ); 	// false
			
      function isFloat(x) {
          return Number.isFinite( x ) && !Number.isInteger( x );
      }
      isFloat( 4.2 );				// true
      isFloat( 4 );				// false
      isFloat( NaN );				// false
      isFloat( Infinity );		// false

      var x = Math.pow( 2, 53 ),
      y = Math.pow( -2, 53 );
      Number.isSafeInteger( x - 1 );	// true
      Number.isSafeInteger( y + 1 ); 	// true
      Number.isSafeInteger( x );		// false
      Number.isSafeInteger( y ); 		// false

5.String
- (1) Unicode Functions
  - String.fromCodePoint(..)
  - String#codePointAt(..)
  - String#normalize(..)
- (2) repeat(..) Prototype Function
  - repeat(..)
    - “foo”.repeat( 3 );
- (3) String Inspection Functions
  - startsWith(..)
  - endsWidth(..)
  - includes(..)

ES6 Chapter 6 API Additions # Other API

3.Math

4.Number

5.String