ludash/lib/flexible.js

export function flexible(options) {
    const docEl = document.documentElement;
    const dpr = window.devicePixelRatio || 1;
    function setRemUnit() {
        let cwidth = docEl.clientWidth;
        if (options.minWidth) {
            cwidth = Math.max(cwidth, options.minWidth);
        }
        const rem = cwidth / 10;
        docEl.style.fontSize = rem + "px";
    }
    setRemUnit();
    window.addEventListener("resize", setRemUnit);
    window.addEventListener("pageshow", function (e) {
        if (e.persisted) {
            setRemUnit();
        }
    });
    if (dpr >= 2) {
        const fakeBody = document.createElement("body");
        const testElement = document.createElement("div");
        testElement.style.border = ".5px solid transparent";
        fakeBody.appendChild(testElement);
        docEl.appendChild(fakeBody);
        if (testElement.offsetHeight === 1) {
            docEl.classList.add("hairlines");
        }
        docEl.removeChild(fakeBody);
    }
}