dojo.byId¶
| since: | V0.3 |
|---|
This is a simple alias to ‘’document.getElementById’‘, which not only is shorter to write, but fortunately works in all browsers. It turns a domNode reference to some Node byId, or the same node reference if passed a domNode.
Since dojo 1.7, dojo.byId is defined in the dojo/dom module. An alias is kept in dojo/_base/html for backward-compatibility.
Usage¶
Dojo 1.7 (AMD)¶
When using AMD in a fully baseless application, byId is accessed from the dojo/dom module.
require(["dojo/dom"], function(dom){
// fetch a node by id="someNode"
var node = dom.byId("someNode");
});
Alternatively, you can load dojo base in AMD style and continue using dojo.byId in the define or require callback:
require(["dojo"], function(dojo){
// fetch a node by id="someNode"
var node = dojo.byId("someNode");
});
Dojo < 1.7¶
// fetch a node by id="someNode"
var node = dojo.byId("someNode");
The node variable is just a native domNode, with properties you can manipulate. The most common, ‘’innerHTML’‘:
// set some node to say "Hello World"
// dojo 1.7 (AMD)
require(["dojo/dom"], function(dom){
dom.byId("someNode").innerHTML = "Hello World";
});
// dojo < 1.7
dojo.byId("someNode").innerHTML = "Hello World";
If you pass byId a domNode reference, the same node is returned:
// dojo 1.7 (AMD)
require(["dojo/dom"], function(dom){
var node = dom.byId("someNode");
var other = dom.byId(node);
console.log(node == other);
});
// dojo < 1.7
var node = dojo.byId("someNode");
var other = dojo.byId(node);
console.log(node == other);
// output
>>> true
If you pass dojo.byId a string, and no domNode is found to match, ‘’undefined’’ or the null object is returned (depending on the browser), which is adequate truthiness to use conditionally:
// dojo 1.7 (AMD)
require(["dojo/dom"], function(dom){
var node = dom.byId("fooBar");
if(node){
node.innerHTML = "I was found!";
}else{
console.log("no node with id='fooBar' found!");
}
});
// dojo < 1.7
var node = dojo.byId("fooBar");
if(node){
node.innerHTML = "I was found!";
}else{
console.log("no node with id='fooBar' found!");
}
Most (if not all) functions in Dojo accept either a string or DomNode as a parameter. If passed a string, the function typically calls dojo.byId(), ensuring a domNode is always the object. For instance:
// dojo 1.7 (AMD)
require(["dojo/dom", "dojo/dom-style"], function(dom, domStyle){
domStyle.set(dom.byId("foo"), "opacity", 0.5);
// is identical to:
domStyle.set("foo", "opacity", 0.5);
});
// dojo < 1.7
dojo.style(dojo.byId("foo"), "opacity", 0.5);
// is identical to:
dojo.style("foo", "opacity", 0.5);
The latter is preferred, as the call to dojo.byId is made in both cases. The passing of a string ID is consistent throughout the Dojo Toolkit.
JavaScript has a fun convention for conditionals inline. Imagine wanting a domNode reference, and if not present, default to some other node:
var othernode = dojo.byId("fallbackNode");
var node = dojo.byId("missingNode") || othernode;
node.innerHTML = "Which one?";
Above, if the node id=”missingNode” is in fact missing, the logical OR will continue, and use othernode as the value of node.
Examples¶
Fade-out a node¶
The following example lets a node by id disappear from the screen
dojo.require("dijit.form.Button");
dojo.ready(function(){
var node = dojo.byId("findMe");
dojo.connect(dijit.byId("buttonOne"), "onClick", function(){
dojo.fadeOut({node: node, duration: 300}).play();
});
dojo.connect(dijit.byId("buttonTwo"), "onClick", function(){
dojo.fadeIn({node: node, duration: 300}).play();
})
});
<button data-dojo-type="dijit.form.Button" id="buttonOne">Hide Me!</button> <button data-dojo-type="dijit.form.Button" id="buttonTwo">Show Me!</button>
<div id="findMe">Hiya!</div>
#findMe {
width: 200px;
height: 100px;
background: #f3f3f3;
border: 1px dotted #ccc;
color: #444;
padding: 10px;
margin: 10px;
}
See Also¶
- dijit.byId - Accessing a Dijit widget by id.