jQuery attribute name as a dynamic variable

Question

I am trying to convert classes to data attributes as i am stuck in a frame work where a can only add classes to button elements.

jQuery("[class*='data_']").each(function (index) {
  
            var classNames = this.className.split(/\s+/);
            for (var i = 0; i < classNames.length; ++i) {
                if (classNames[i].substr(0, 5) === "data_") {
                   ctargets = classNames[i].slice(5);
                   var target = "data-" + ctargets.split('-')[0];
                   var target_length = (target.length -4);
                   var value = ctargets.slice(target_length);
                  jQuery(this).attr({target:value});
                }
            }
        });

But this literally adds target="value" to my element not data-variable="value"

Answer 1

You could achieve this with a lot less string manipulation (and a lot less jQuery)

const t1 = performance.now()

// A regex test for data_attr-
const rx = /^data_\w+-/

document.querySelectorAll("[class*='data_']").forEach(el => {
  Array.from(el.classList).filter(c => rx.test(c)).forEach(c => {
    const [ dataAttr, value ] = c.split(/-(.+)/)
    el.setAttribute(dataAttr.replace("_", "-"), value)
  })
})

const t2 = performance.now()

document.getElementById("out").textContent = document.getElementById("in").innerHTML

console.log(`Operation took ${t2 - t1}ms`)

pre { white-space: pre-line; }

<div id="in">
<a class="mirror data_target-home-machines" href="#">Home Machines</a>
</div>
<pre id="out"></pre>

---

Special thanks to this answer for that awesome String.prototype.split() trick