JavaScript advanced Programming--syntax, keywords, reserved words, variables, data types

1, understand the basic grammar, JS case-sensitive, annotation style, what is strict mode and so on.

2, know ES3 and ES5 keywords and reserved words about what, if the use of keywords will be reported what wrong, using reserved words determined by the specific browser engine.

3, the definition of global variables and local variables, why not recommend the use of the shape: message= "HI" such as global variables.

4, know 6 kinds of data type, typeof return value and so on.

Some questions:

A, how to determine whether a variable is defined or initialized?

b, define a variable, prepare to save the object, how to initialize it?

C, alert (undefined==null) output what?

D, what is the value of the automatic Boolean conversion for other data types?

E, 0.1+0.2==0.3?

What is the range of F and JS values? How can I tell if I'm out of bounds?

What is the isNaN return value for the definition of G, Nan, and other data types?

h, numeric conversion number (), parseint (), parsefloat () The difference and contact?

What is the difference between the I, ToString, and string methods?

What are the methods commonly used for J and object types?

JavaScript advanced Programming--syntax, keywords, reserved words, variables, data types