JavaScript Basics Review A

Javascript

first, the data type

A, String

B, number

C, Boolean

1, undefined, false, null, 0, "" The five returned is false;

2, Nan==nan return false,undefined==undefined true;

D, undefined

E, NULL

Summary: There are five types of data in JavaScript and you can use typeof to determine the data type.

Ii. Conversion of data types

A, Cast

a, toString () (undefined and null do not have a string METHOD)

b, String () (universal Conversion)

Nan converts to number

B, Implicit conversion

a, value+ ';

third, the circular statement

A, for statement

B, while Statement (the Whie statement is used when the number of cycles is not determined)

C, do. While statement (requires first operation before judging the loop condition, use the Do...while statement)

Iv. conditional statements

A, If statement

B, If...else Statement (two branches)

C, If: Else If...else Statement (multipath Branch)

V. Jump statements

A, Switch...case Statement

Vi. operators

Arithmetic operators

logical operators

Ternary operators

JavaScript Basics Review A