JavaScript Swipe Validation

Because I am making a portal website, I need to use js sliding verification.

original

https://blog.csdn.net/chy555chy/article/details/55294147

html

   <div id="dragContainer">
        <div id="dragBg"></div>
        <div id="dragText"></div>
        <div id="dragHandler" class="dragHandlerBg"></div>
    </div>

css

  <style>
        /* Sliding control container, light gray background */
        #dragContainer {
            position: relative;
            display: inline-block;
            background: #e8e8e8;
            width: 300px;
            height: 50px;
            border: 2px solid #e8e8e8;
        }
        /* The left part of the slider, green background */
        #dragBg {
            position: absolute;
            background-color: #7ac23c;
            width: 0px;
            height: 100%;
        }
        /* Swipe validation container text */
        #dragText {
            position: absolute;
            width: 100%;
            height: 100%;
            /* Center the text horizontally */
            text-align: center;
            /* The text is vertically centered, the percentage cannot be used here, because the percentage is relative to the original line-height, not the div height*/
            line-height: 50px;
            /* Text is not allowed to be selected */
            user-select: none;
            -webkit-user-select: none;
        }
        /* slider */
        #dragHandler {
            position: absolute;
            width: 50px;
            height: 100%;
            cursor: move;
        }
        /* Slider initial background */
        .dragHandlerBg {
            background: #fff no-repeat center url("data:image/png;base64,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");
        }
        /* Slider background when authentication is successful */
        .dragHandlerOkBg {
            background: #fff no-repeat center url("data:image/png;base64,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");
        }
    </style>
    <script>
        window.onload = function() {
            var dragContainer = document.getElementById("dragContainer");
            var dragBg = document.getElementById("dragBg");
            var dragText = document.getElementById ("dragText");
            var dragHandler = document.getElementById ("dragHandler");

            //slider maximum offset
            var maxHandlerOffset = dragContainer.clientWidth - dragHandler.clientWidth;
            //Whether the verification is successful mark
            var isVertifySucc = false;
            initDrag ();

            function initDrag() {
                dragText.textContent = "Drag slider validation";
                dragHandler.addEventListener("mousedown", onDragHandlerMouseDown);

                dragHandler.addEventListener("touchstart", onDragHandlerMouseDown);
            }

            function onDragHandlerMouseDown(event) {
                document.addEventListener("mousemove", onDragHandlerMouseMove);
                document.addEventListener("mouseup", onDragHandlerMouseUp);

                document.addEventListener("touchmove", onDragHandlerMouseMove);
                document.addEventListener("touchend", onDragHandlerMouseUp);
            }

            function onDragHandlerMouseMove(event) {
                /*
                There is no width attribute on the html element, only clientWidth
                offsetX is relative to the current element, clientX and pageX are relative to its parent element

                touches: An array of touch objects representing the currently tracked touch operations.
                targetTouches: An array of Touch objects specific to the event target.
            　　changedTouches: An array of Touch objects representing what has changed since the last touch.
                */
                var left = (event.clientX || event.changedTouches[0].clientX) - dragHandler.clientWidth / 2;
                if(left < 0) {
                    left = 0;
                } else if(left > maxHandlerOffset) {
                    left = maxHandlerOffset;
                    verifySucc();
                }
                dragHandler.style.left = left + "px";
                dragBg.style.width = dragHandler.style.left;
            }
            function onDragHandlerMouseUp(event) {
                document.removeEventListener("mousemove", onDragHandlerMouseMove);
                document.removeEventListener("mouseup", onDragHandlerMouseUp);

                document.removeEventListener("touchmove", onDragHandlerMouseMove);
                document.removeEventListener("touchend", onDragHandlerMouseUp);

                dragHandler.style.left = 0;
                dragBg.style.width = 0;
            }

            //Verification succeeded
            function verifySucc() {
                isVertifySucc = true;
                dragText.textContent = "Verification passed";
                dragText.style.color = "white";
                dragHandler.setAttribute("class", "dragHandlerOkBg");

                dragHandler.removeEventListener("mousedown", onDragHandlerMouseDown);
                document.removeEventListener("mousemove", onDragHandlerMouseMove);
                document.removeEventListener("mouseup", onDragHandlerMouseUp);

                dragHandler.removeEventListener("touchstart", onDragHandlerMouseDown);
                document.removeEventListener("touchmove", onDragHandlerMouseMove);
                document.removeEventListener("touchend", onDragHandlerMouseUp);
            };
        }
    </script>

before swiping

after swiping