JavaScript DOM HTML method: hasAttribute()
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The hasAttribute() method (when applied to
HTML
elements in the JavaScript
DOM) returns true if the element has the specified
attribute, otherwise it returns false.
It
has the following syntax with the following parameters. It returns a
Boolean as above.
element.hasAttribute(attributename)
|
Parameter
|
Required / Optional
|
Description
|
|
attributename
|
Required
|
String containing name
of attribute
|
EXAMPLE:
HTML USED IN THIS EXAMPLE:
<!DOCTYPE html>
<html> <!-- Copyright (c) Nematrian Limited 2018 -->
<head></head>
<body>
<span id="element"></span><br>
<span id="element2"></span>
<script>
var x2 = document.createElement("CANVAS");
x2.setAttribute("width","150");
x2.setAttribute("height","70");
x2.setAttribute("style","border: 1px solid black");
var c2 = x2.getContext("2d");
c2.fillStyle = "blue";
c2.font = "40px Verdana";
c2.shadowBlur = "4";
c2.shadowColor = "red";
c2.shadowOffsetX = "2";
c2.shadowOffsetY = "3";
c2.fillText("Hello", 10, 50);
document.getElementById("element").appendChild(x2);
var a = x2.attributes;
var ct = a.length;
document.getElementById("element2").innerHTML =
"Has attributes? " + x2.hasAttributes() + "<br>" +
"Has width attribute? " + x2.hasAttribute("width") + "<br>" +
"Width attribute using getAttribute = " + x2.getAttribute("width") + "<br>" +
"Number of attributes = " + ct + ", i.e.:<br>" +
" " + a[0].name + " = " + a[0].value + "<br>" +
" " + a[1].name + " = " + a[1].value + "<br>" +
" " + a[2].name + " = " + a[2].value + "<br>";
</script>
</body>
</html>
|
FUNCTION THAT MAY ASSIST IN TESTING WHETHER FEATURE IS SUPPORTED:
function isSupportedJavaScriptMethodDomHtmlHasAttribute() {
var z = document.createElement("TABLE"); return !!z.hasAttribute;
} |
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