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Using the Same Callback on Multiple Elements2:30 with Andrew Chalkley
In this video we'll use the same callback for multiple HTML elements.
How did you do? 0:00 I copied both nameInput events and pasted them down here and 0:01 replaced nameInput with messageTextArea. 0:07 While this is fine, we have some repetition in our code. 0:12 We have the focus handler twice and the blur handler twice. 0:16 We can remove the repetition by moving these event handlers into 0:24 functions with names. 0:28 I'll create two variables, 0:30 const focusHandler and const blurHandler. 0:34 Now we can move the handlers out of the addEventListener and 0:45 assign them to the appropriate variable names. 0:50 Now we can pass in the names of the functions as callbacks to 0:56 the addEventListener method calls. 1:00 Avoiding repetition in your code is referred to as DRY or 1:23 don't repeat yourself. 1:27 Look for opportunities for sensible places to avoid duplicate code. 1:29 As you practice this will become more natural to you. 1:33 Our code has one function to handle all the focus events. 1:37 For the input, And the text area elements. 1:42 And another function that handles all the blur effects. 1:48 Remember addEventListener will pass in an events object to the callback. 1:53 The event object has an associated target. 1:59 Remember that the addEventListener will pass in the event object with 2:03 the associated target element for the event if the focus event 2:07 is triggered on the input, then the event.target will be the input. 2:13 If the focus event is triggered on the text area element, 2:22 the event.target will be the text area. 2:26
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