JavaScript exploration: Using parseInt () for Numerical Conversion

You can use parseInt () to obtain a value from a string. This method accepts another base parameter

You can use parseInt () to obtain a value from a string. This method accepts another base parameter, which is often omitted, but should not. A problem may occur when the string starts with "0". For example, if you enter the form field for some time, In ECMAScript 3, the string starting with "0" is treated as an octal string, but this has changed in ECMAScript 5. To avoid conflicts and unexpected results, the base parameter is always specified.

var month = "05",    year = "09";month = parseInt(month, 10);year = parseInt(year, 10);alert(month);alert(year);

Script var month = "05", year = "09"; month = parseInt (month, 10); year = parseInt (year, 10); var btn1 = document. getElementById ("btn1"); btn1.onclick = function () {alert (month); alert (year);} script

In this example, if you ignore the base parameter, for example, parseInt (year), the returned value is 0, because "09" is treated as an octal (like executing parseInt (year, (8), and 09 is not a valid number in the octal format.

The replacement method is to convert the string to a number, including:

+ "08" // The result is 8 Number ("08") // 8

These are usually faster than parseInt (), because parseInt () method is not simply parsed and converted. However, if you want to enter "08 hello", parseInt () will return a number, and the rest will end with NaN.

Additional reading

The topic list of this article is as follows:

1. How should we understand the working principle of the JavaScript engine?
2. JavaScript exploration: the importance of writing maintainable code
3. JavaScript exploration: exercise caution when using global variables
4. JavaScript exploration: var pre-parsing and side effects
5. JavaScript exploration: for Loop (for Loops)
6. JavaScript exploration: for-in loop (for-in Loops)
7. Exploring JavaScript: Prototypes is too powerful
8. JavaScript: eval () is the devil"
9. JavaScript exploration: Using parseInt () for Numerical Conversion
10. Exploring JavaScript: Basic coding specifications
11. JavaScript exploration: function declaration and function expression
12. JavaScript exploration: Name function expressions
13. JavaScript: function name in the debugger
14. JavaScript: JScript Bug
15. JavaScript exploration: Memory Management of JScript
16. Exploring JavaScript: SpiderMonkey's quirks
17. JavaScript exploration: an alternative solution to naming function expressions
18. JavaScript exploration: Object
19. JavaScript exploration: Prototype chain
20. JavaScript exploration: Constructor
21. JavaScript probing: executable context Stack
22. Execution context 1: Variable object and activity object
23. Execution context 2: Scope chain Scope Chains
24. Execution context 3: Closure Closures
25. Execution context 4: This pointer
26. Exploring JavaScript: Powerful prototype and prototype chain
27. JavaScript Functions 1: function declaration
28. JavaScript function 2: function expressions
29. JavaScript function 3: function expressions in a group
30. JavaScript function 4: function Constructor
31. JavaScript variable object 1: VO Declaration
32. JavaScript variable object 2: VO in different execution contexts
33. JavaScript variable object 3: two stages of execution Context
34. JavaScript variable object IV: Variables
35. Property of the JavaScript variable object __parent _
36. JavaScript scope chain 1: Scope chain Definition
37. JavaScript scope chain 2: function Lifecycle
38. JavaScript scope chain 3: Scope chain features
39. JavaScript closure 1: Introduction to closures
40. JavaScript closure 2: Implementation of closure
41. JavaScript closure 3: Closure usage

This article is available at http://www.nowamagic.net/librarys/veda/detail/1628.