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Detailed explanation of how to use functions to add and perform actions in WordPress, detailed explanation of wordpress_PHP tutorial
- WBOYOriginal
- 2016-07-12 09:02:091144browse
Detailed explanation of how to use functions to add and execute actions in WordPress, detailed explanation of wordpress
add_action() (add action)
The add_action() function is used to mount a function to the action hook.
Usage
add_action( $tag, $function_to_add, $priority, $accepted_args );
Parameters
$hook
(String) (Required) The action name of the mounted function.
Default value: None
$function_to_add
(Callback function) (required) The function to be mounted, just fill in the function name in the form of a string.
Default value: None
$priority
(integer) (optional) The priority of action execution. The smaller the value, the first it will be executed.
Default value: 10
$accepted_args
(integer) (optional) The callback function receives several parameters.
Default value: 1
Return value
(Boolean) always returns True.
Example
Mount a function to the wp_head action and print something in the head tag.
function Bing_wp_head_test_print(){
echo '<meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=0" />';
}
add_action( 'wp_head', 'Bing_wp_head_test_print' );
Others
This function is located at: wp-includes/plugin.php
do_action() (execute action)
do_action() is used to execute action hooks. The difference between it and apply_filters() is that there is no return value. It simply executes the function mounted by the plug-in or theme developer in a specific place, which generally exists in a special node. Or on events (such as when starting to load the theme template or when publishing an article).
Usage
do_action( $tag, $arg... );
Parameters
$tag
(String) (Required) The name of the action to perform.
$arg
(Mixed) (optional) Additional parameters will be passed to the called function. Unlimited numbers can be added. For example, when the save_post action is triggered when saving an article, the id of the saved article can be inserted into the callback. The function operates based on the article id.
Return value
None
Example
function func(){
echo '测试';
}
add_action( 'test', 'func' );
do_action( 'test' );
Screen printing:
Test
For more reference, apply_filters(): http://www.endskin.com/apply_filters/
Others
This function is located at: wp-includes/plugin.php
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