Chrome doesn't fire click event for SVG element (Firefox does)

问题

I observe inconsistency/bug in handling click event among various browsers (Chrome, Edge, Firefox).

In my JavaScript library that uses SVG I create clickable and draggable rectangles. When I run my snippet in Chrome browser the click event is not firing if 2 or more elements are present on canvas.

To check this you need to create at least 2 rectangles on canvas. You can drag them with mouse (Rectangles initial position is the same). Normally rectangle's border become brown if click event was fired on element.

The strange things is that Firefox fires click event as expected but Chrome doesn't fire the event at all. MS Edge browser fires click event on double-click.

P.S: The code is presented here in full capacity so you can run the example:

"use strict";
var SVGCanvas = undefined;
var canvClientRect = {};

function initScript() {
    SVGCanvas = document.getElementById("playSVGCanvas");
    canvClientRect.width = SVGCanvas.getClientRects()[0].width;
    canvClientRect.height = SVGCanvas.getClientRects()[0].height;
}

function createRect() {
    var newRect = document.createElementNS("http://www.w3.org/2000/svg", "rect");

    var rectX0 = 20;
    var rectY0 = 20;
    var rectWidth = 100;
    var rectHeight = 50;

    newRect.setAttributeNS(null, "x", rectX0);
    newRect.setAttributeNS(null, "y", rectY0);
    newRect.setAttributeNS(null, "width", rectWidth);
    newRect.setAttributeNS(null, "height", rectHeight);
    newRect.setAttributeNS(null, "class", "draggable rect inactive");
    newRect.setAttributeNS(null, "onmousedown", "selectElement(evt)");
    newRect.setAttributeNS(null, "onclick", "clickHandler(evt)");
    SVGCanvas.appendChild(newRect);
}

var currentX = 0;
var currentY = 0;
var shapeWidth = undefined;
var shapeHeight = undefined;

var wasMoved = false;


function selectElement(evt) {
    evt.preventDefault();
    var targetEl = evt.target;
    currentX = evt.clientX;
    currentY = evt.clientY;
    shapeWidth = targetEl.getAttributeNS(null, "width");
    shapeHeight = targetEl.getAttributeNS(null, "height");

    if (SVGCanvas.childElementCount >= 2) {
        // change element's order to show selected item on the top
        SVGCanvas.appendChild(targetEl);
    }

    targetEl.setAttributeNS(null, "onmousemove", "moveElement(evt)");
    targetEl.setAttributeNS(null, "onmouseout", "deselectElement(evt)");
    targetEl.setAttributeNS(null, "onmouseup", "deselectElement(evt)");

    wasMoved = false;
}

function moveElement(evt) {
    evt.preventDefault();
    var targetEl = evt.target;

    var dx = evt.clientX - currentX;
    var dy = evt.clientY - currentY;
    currentX = evt.clientX;
    currentY = evt.clientY;
    var newX = parseInt(targetEl.getAttributeNS(null, "x")) + dx;
    var newY = parseInt(targetEl.getAttributeNS(null, "y")) + dy;

    if(newX < 0) {
        targetEl.setAttributeNS(null, "x", 0);
    } else if (newX > canvClientRect.width - shapeWidth) {
        targetEl.setAttributeNS(null, "x", canvClientRect.width - shapeWidth);
    } else {
        targetEl.setAttributeNS(null, "x", newX);
    }

    if (newY < 0) {
        targetEl.setAttributeNS(null, "y", 0);
    } else if (newY > canvClientRect.height - shapeHeight) {
        targetEl.setAttributeNS(null, "y", canvClientRect.height - shapeHeight);
    } else {
        targetEl.setAttributeNS(null, "y", newY);
    }

    wasMoved = true;
}

function deselectElement(evt) {
    if (evt == null) {
        console.log("Event == null");
        return;
    }
    evt.target.removeAttributeNS(null, "onmousemove");
    evt.target.removeAttributeNS(null, "onmouseout");
    evt.target.removeAttributeNS(null, "onmouseup");
}

function clickHandler(evt) {
    // click event fires even element was moved
    // we don't handle click if element was moved
    if (wasMoved) { return; }

    var targetEl = evt.target;
    if (targetEl.classList.contains("active")) {
        deActivateElm(targetEl);
    } else {
        activateElm(targetEl);
    }
}

function activateElm(elm) {
    elm.classList.remove("inactive");
    elm.classList.add("active");
}

function deActivateElm(elm) {
    elm.classList.remove("active");
    elm.classList.add("inactive");
}

#workCanv {
    width: 100%;
    height: 180px;
    border: 1px solid black;
}

.draggable {
    cursor: move;
}

.rect {
    stroke-width: 4;
    fill: lightgrey;
}

.active {
    stroke: brown
}

.inactive {
    stroke: black
}

<!DOCTYPE html>
<head>
    <meta charset="utf-8">
    <link rel="stylesheet" type="text/css" href="wcstyle.css">
    <script src="wccontroller.js"></script>
</head>

<body onload="initScript()">

<div id="panel">
    <button type="button" name="addRectagble" onclick="createRect()">Add rectangle</button>
</div>

<div id="workCanv">
    <svg xmlns="http://www.w3.org/2000/svg" height="100%" width="100%" id="playSVGCanvas">
    </svg>
</div>
</body>

回答1:

After some time I reported this question to Chrome dev team because I thought it is a bug. But it's not. The behavior for cases when an element is removed from the document tree and then added back before mouseup (e.g. appendChild(lastChild)) is not defined yet by W3 committee. As result behavior varies from browser to browser.

Progress for the problem can be tracked with following links:

1. Chrome issue thread

2. W3C issue discussion thread

来源：https://stackoverflow.com/questions/37921993/chrome-doesnt-fire-click-event-for-svg-element-firefox-does