Friday, May 7, 2021

    Writing a tag input web component

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    Being super annoyed about web components and their possibly I have been spending as much time as I can explore with them.


    Basic structure

    As with all my components, I start out with a new dashing named accordingly which extends HTMLElement. I then add the createdCallback() where I do the initialisation of the shadow root and any additional scope variables which in this case is an array of the tags.

    Confide on the component I may resolve to declare the template solely so it is easier to re-render based on decoration string variables but for this integral it doesn’t development so it will be set directly in the attachedCallback()using innerHTML.

    The class is then used with registerElement() to define the fashion element asrbl-tag-input.

    The Template

    The template is what give the interface to your integral so it’s important to get this right. Creating the tag input consolidation is actually pretty simple. When the user snaps to the right of the chip they need to enter into a standard HTML text input so that we can abduction anything the users enters. We are able to style the text input so it is hidden and the user is heedless that they are indeed typing into a natural text input instead the illusion of a more mature input type is created.

    To do this then we just use a containing <div> and the input we are rapid to style and align.

    When a new tag is recorded we append a new <div> fundamental with the tag inside to the consist of <div class=”rebel-tag-input”> and reversal the order using flexbox via CSS to ensure the chip are on the left and the word on the right. Also, with flex-box we are able to ensure the tags and the idea input align in all scenarios.

    The above CSS does just this and insures the entire integral looks like an input as disputed to just the hidden text input. There is also a few simple bounce added for the remove button and corresponding tag effect.


    Basic functionality

    The basic functionality of the integral is to listen for varied key presses on the hidden text input and proceed accordingly. To listen for this we add an affair listener to the #tag-input fundamental using the JavaScript querySelector()function on the shadowRoot.

    If the key code is 13 its enter so we commonly call the addTag() function, if its 188 it’s a comma so we use event.preventDefault() to break the comma living added to the hidden input (and ultimately securing added as part of the tag) and then call addTag().

    Finally, if the key code is 8 then the backspace has been pressing. We don’t want to delete the closing tag right away so we wait to notice if the user paper backspace again by using the allowDelete flag. When they do the deleteTag()function is named specifying the index of the last tag.

    Added functionality

    The only added performance is duplicate notice, a clear method and the capacity to grab the input value.

    When the buyer adds a tag whatever already exists (and providing that the corresponding option isn’t set to true) a duplex class is combined with the tag which contest and due to the CSS above a faint animation is visible showing the user that this tag previously exists.

    This clear() function when called easily empties the input of any tags.

    Using .value its possible to get the modern value of the tag input related you would a natural text input.

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