jquery's append not working with svg element?-第2页回答

Assuming this:

<html>
<head>
 <script type="text/javascript" src="jquery.js"></script>
 <script type="text/javascript">
 $(document).ready(function(){
  $("svg").append('<circle cx="100" cy="50" r="40" stroke="black" stroke-width="2" fill="red"/>');
 });
 </script>
</head>
<body>
 <svg xmlns:svg="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 100" width="200px" height="100px">
 </svg>
</body>

Why don't I see anything?

标签： jquery html5 svg

14条回答

浅入江南

2楼-- · 2018-12-31 01:34

When you pass a markup string into $, it's parsed as HTML using the browser's innerHTML property on a <div> (or other suitable container for special cases like <tr>). innerHTML can't parse SVG or other non-HTML content, and even if it could it wouldn't be able to tell that <circle> was supposed to be in the SVG namespace.

innerHTML is not available on SVGElement—it is a property of HTMLElement only. Neither is there currently an innerSVG property or other way(*) to parse content into an SVGElement. For this reason you should use DOM-style methods. jQuery doesn't give you easy access to the namespaced methods needed to create SVG elements. Really jQuery isn't designed for use with SVG at all and many operations may fail.

HTML5 promises to let you use <svg> without an xmlns inside a plain HTML (text/html) document in the future. But this is just a parser hack(**), the SVG content will still be SVGElements in the SVG namespace, and not HTMLElements, so you'll not be able to use innerHTML even though they look like part of an HTML document.

However, for today's browsers you must use XHTML (properly served as application/xhtml+xml; save with the .xhtml file extension for local testing) to get SVG to work at all. (It kind of makes sense to anyway; SVG is a properly XML-based standard.) This means you'd have to escape the < symbols inside your script block (or enclose in a CDATA section), and include the XHTML xmlns declaration. example:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"><head>
</head><body>
    <svg id="s" xmlns="http://www.w3.org/2000/svg"/>
    <script type="text/javascript">
        function makeSVG(tag, attrs) {
            var el= document.createElementNS('http://www.w3.org/2000/svg', tag);
            for (var k in attrs)
                el.setAttribute(k, attrs[k]);
            return el;
        }

        var circle= makeSVG('circle', {cx: 100, cy: 50, r:40, stroke: 'black', 'stroke-width': 2, fill: 'red'});
        document.getElementById('s').appendChild(circle);
        circle.onmousedown= function() {
            alert('hello');
        };
    </script>
</body></html>

*: well, there's DOM Level 3 LS's parseWithContext, but browser support is very poor. Edit to add: however, whilst you can't inject markup into an SVGElement, you could inject a new SVGElement into an HTMLElement using innerHTML, then transfer it to the desired target. It'll likely be a bit slower though:

<script type="text/javascript"><![CDATA[
    function parseSVG(s) {
        var div= document.createElementNS('http://www.w3.org/1999/xhtml', 'div');
        div.innerHTML= '<svg xmlns="http://www.w3.org/2000/svg">'+s+'</svg>';
        var frag= document.createDocumentFragment();
        while (div.firstChild.firstChild)
            frag.appendChild(div.firstChild.firstChild);
        return frag;
    }

    document.getElementById('s').appendChild(parseSVG(
        '<circle cx="100" cy="50" r="40" stroke="black" stroke-width="2" fill="red" onmousedown="alert(\'hello\');"/>'
    ));
]]></script>

**: I hate the way the authors of HTML5 seem to be scared of XML and determined to shoehorn XML-based features into the crufty mess that is HTML. XHTML solved these problems years ago.

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裙下三千臣

3楼-- · 2018-12-31 01:34

The accepted answer shows too complicated way. As Forresto claims in his answer, "it does seem to add them in the DOM explorer, but not on the screen" and the reason for this is different namespaces for html and svg.

The easiest workaround is to "refresh" whole svg. After appending circle (or other elements), use this:

$("body").html($("body").html());

This does the trick. The circle is on the screen.

Or if you want, use a container div:

$("#cont").html($("#cont").html());

And wrap your svg inside container div:

<div id="cont">
    <svg xmlns:svg="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 100" width="200px" height="100px">
    </svg>
</div>

The functional example:
http://jsbin.com/ejifab/1/edit

The advantages of this technique:

you can edit existing svg (that is already in DOM), eg. created using Raphael or like in your example "hard coded" without scripting.
you can add complex element structures as strings eg. $('svg').prepend('<defs><marker></marker><mask></mask></defs>'); like you do in jQuery.
after the elements are appended and made visible on the screen using $("#cont").html($("#cont").html()); their attributes can be edited using jQuery.

EDIT:

The above technique works with "hard coded" or DOM manipulated ( = document.createElementNS etc.) SVG only. If Raphael is used for creating elements, (according to my tests) the linking between Raphael objects and SVG DOM is broken if $("#cont").html($("#cont").html()); is used. The workaround to this is not to use $("#cont").html($("#cont").html()); at all and instead of it use dummy SVG document.

This dummy SVG is first a textual representation of SVG document and contains only elements that are needed. If we want eg. to add a filter element to Raphael document, the dummy could be something like <svg id="dummy" style="display:none"><defs><filter></filter></defs></svg>. The textual representation is first converted to DOM using jQuery's $("body").append() method. And when the (filter) element is in DOM, it can be queried using standard jQuery methods and appended to the main SVG document which is created by Raphael.

Why this dummy is needed? Why not to add a filter element strictly to Raphael created document? If you try it using eg. $("svg").append("<circle ... />"), it is created as html element and nothing is on screen as described in answers. But if the whole SVG document is appended, then the browser handles automatically the namespace conversion of all the elements in SVG document.

An example enlighten the technique:

// Add Raphael SVG document to container element
var p = Raphael("cont", 200, 200);
// Add id for easy access
$(p.canvas).attr("id","p");
// Textual representation of element(s) to be added
var f = '<filter id="myfilter"><!-- filter definitions --></filter>';

// Create dummy svg with filter definition 
$("body").append('<svg id="dummy" style="display:none"><defs>' + f + '</defs></svg>');
// Append filter definition to Raphael created svg
$("#p defs").append($("#dummy filter"));
// Remove dummy
$("#dummy").remove();

// Now we can create Raphael objects and add filters to them:
var r = p.rect(10,10,100,100);
$(r.node).attr("filter","url(#myfilter)");

Full working demo of this technique is here: http://jsbin.com/ilinan/1/edit.

( I have (yet) no idea, why $("#cont").html($("#cont").html()); doesn't work when using Raphael. It would be very short hack. )

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不再属于我。

4楼-- · 2018-12-31 01:34

I can see circle in firefox, doing 2 things:

1) Renaming file from html to xhtml

2) Change script to

<script type="text/javascript">
$(document).ready(function(){
    var obj = document.createElementNS("http://www.w3.org/2000/svg", "circle");
    obj.setAttributeNS(null, "cx", 100);
    obj.setAttributeNS(null, "cy", 50);
    obj.setAttributeNS(null, "r",  40);
    obj.setAttributeNS(null, "stroke", "black");
    obj.setAttributeNS(null, "stroke-width", 2);
    obj.setAttributeNS(null, "fill", "red");
    $("svg")[0].appendChild(obj);
});
</script>

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何处买醉

5楼-- · 2018-12-31 01:39

The increasingly popular D3 library handles the oddities of appending/manipulating svg very nicely. You may want to consider using it as opposed to the jQuery hacks mentioned here.

HTML

<svg xmlns="http://www.w3.org/2000/svg"></svg>

Javascript

var circle = d3.select("svg").append("circle")
    .attr("r", "10")
    .attr("style", "fill:white;stroke:black;stroke-width:5");

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若你有天会懂

6楼-- · 2018-12-31 01:39

Based on @chris-dolphin 's answer but using helper function:

// Creates svg element, returned as jQuery object
function $s(elem) {
  return $(document.createElementNS('http://www.w3.org/2000/svg', elem));
}

var $svg = $s("svg");
var $circle = $s("circle").attr({...});
$svg.append($circle);

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低头抚发

7楼-- · 2018-12-31 01:39

 var svg; // if you have variable declared and not assigned value.
 // then you make a mistake by appending elements to that before creating element    
 svg.appendChild(document.createElement("g"));
 // at some point you assign to svg
 svg = document.createElementNS('http://www.w3.org/2000/svg', "svg")
 // then you put it in DOM
 document.getElementById("myDiv").appendChild(svg)
 // it wont render unless you manually change myDiv DOM with DevTools

// to fix assign before you append
var svg = createElement("svg", [
    ["version", "1.2"],
    ["xmlns:xlink", "http://www.w3.org/1999/xlink"],
    ["aria-labelledby", "title"],
    ["role", "img"],
    ["class", "graph"]
]);
function createElement(tag, attributeArr) {
      // .createElementNS  NS is must! Does not draw without
      let elem = document.createElementNS('http://www.w3.org/2000/svg', tag);             
      attributeArr.forEach(element => elem.setAttribute(element[0], element[1]));
      return elem;
}
// extra: <circle> for example requires attributes to render. Check if missing.

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jquery's append not working with svg element?

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