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11th. Obtaining Geo-location information
HTML5 adds a Geolocation property to the Window.navigator object
Get Current Location
void GetCurrentPosition (onsuccess,onerror,options);
The first parameter is the callback function that gets executed successfully, the second is the callback function executed on failure, and the third is a list of optional properties (the second and third optional)
Navigator.geolocation.getCurrentPosition (function (position) {
Get processing when successful (parameter position is a position object)
})
The second parameter of the GetCurrentPosition method is the function called when it gets failed, which can be a prompt box, etc.
When the browser asks the user whether to share the location information, select No also throws an error, the callback function has an Error object with two properties
Code attribute: User denied location service (value 1) gets no location information (value 2) gets information timeout error (value 3)
Message property: Is a string that contains the error message and is useful when debugging
The third parameter of the GetCurrentPosition method can be:
Enablehighaccuracy: Whether high-precision geo-location information is required, it is necessary to consider the power of the equipment, the specific geographical situation, in most cases the default
Timeout: A time-limited operation (in milliseconds) to get operations on geo-location information, which returns an error if not obtained in the specified period
Maximumage: The effective time (in milliseconds) to cache geo-location information and try to get information again after it expires
Navigator.geolocation.getCurrentPosition (
function (position) {...},
Function (Error) {...},
{maximumage:60*1000*2,timeout:5000}
)
Continuous monitoring of current geo-location information (automatically acquired on a regular basis)
int watchcurrentposition (onsuccess,onerror,options);
The parameter is the same as the GetCurrentPosition method, and returns a number that can be used by the Clearwatch method to stop monitoring
Stop void Clearwatch (Watchid);
Position object: After obtaining a successful location, the callback function called to access the properties of the Position object
Latitude: Dimensions
Longitude: Longitude
Altitude: altitude, cannot be fetched or null
Accuracy accuracy of longitude and latitude (m)
Altitudeaccurancy altitude accuracy (m)
Heading device's forward method, which is the clockwise angle of the true north, which cannot be obtained is NULL
Speed device advance, cannot be obtained or null (M/s)
Timestamp time when acquiring a location
12th Chapter CSS3 Overview
In the CSS3, the overall structure is not adopted, but the modular structure of division and cooperation is adopted.
The advantage of modular is to prevent some browsers from not fully supporting some features, split into multiple modules to gradually support
3rd Chapter Selector
The disadvantages of specifying class in a style are: class itself has no semantics; use confusion
Property selector [Att*=val][att^=val][att$=val]
Structural pseudo-Class selectors
A pseudo-class selector is a selector that is already defined in the CSS and cannot be renamed (":")
A:link a:visited a:hover a:active first-line First-letter before after
Root selector: Binds a style to the root element of the page (entire <HTML>)
Not selector: Excludes sub-structure elements below this structure element
Empty selector: Specifies the style used when the content of the element is blank
Target selector: <a href= "#text1" > Text </a>, and jump to the style of change when ID equals Text1
First-child last-child Nth-child (: Nth-child (3) 3rd element if odd is odd) and Nth-last-child (: Nth-last-child (3) The 3rd element if even is an even number)
Nth-of-type and Nth-last-of-type, sorted by type, the above example refers to one of the odd elements of all elements, which refers to one of the all odd elements
Only-child selector: Apply a style when there is only one child element
UI element state pseudo class Selector
In addition to the structural pseudo-class selectors, there are UI element State pseudo-class selectors
: hover:active:focus:enabled (available):d isabled(not available): read-only (read-only readonly= "ReadOnly"): Read-write (not read-only): The Checked (Radio checkbox or CheckBox check box is selected, Firefox must be written as-moz-checked):d Efault (the radio or check box is selected by default): Indeterminate (any single box is not set to the overall style when selected, the user selects one of the styles is canceled): Selection (element is selected)
Universal Sibling Element Selector
< child elements >-< sibling elements after child elements >{}
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