Fifteen years ago, when "Web 2.0" was a thing, Ben Nolan's Behaviour.js enlightened me to the virtues of declarative programming.  Developing for a web-browser really lends itself to this approach.  Using "sheets" to target particular JavaScript code at selected DOM elements provides a way to separate, in a consistent way, the behaviorial aspects of a web-page.  For a while I'd subscribed to his advice to use JQuery instead, and this was incredibly effective but always felt like I was cheating.  Including JQuery in a web-page for a tiny bit of convenience was just heavy handed.  Now, 15 years later, I've finally weened myself off of that crutch too.  Below is a tiny scrap of JavaScript that leverages the native JavaScript Document.querySelectorAll() function...

function attachBehaviors(behaviors) {
    Object.entries(behaviors).forEach(([selector, behavior], index) => {
        document.querySelectorAll(selector).forEach(elm => {
            behavior.call(this, index, elm);
        });
    });
}
export {attachBehaviors};

With this function available, now pass a "sheet"...

attachBehaviors({
    'a.externallink': function(idx, elm) {
        elm.addEventListener('click', function(evt) {
            evt.preventDefault();
            window.open(evt.target.href);
        });
    },
    'form#uploadForm': function(idx, elm) {
        elm.addEventListener('submit', function(evt) {
            evt.preventDefault();
            processFiles();
        });
    }
});

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Posted by Wyatt on August 10, 2021 6:28:43 AM EDT #