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dojo/dom

Project owner:Eugene Lazutkin
since:V1.7

This module defines the core Dojo DOM API. The standard return variable for this module is dom.

The deprecated legacy features are set in dojo/_base/html.

Features

byId()

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.

Usage

The basic usage is very straight forward:

require(["dojo/dom"], function(dom){
    // fetch a node by id="someNode"
    var node = dom.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"
require(["dojo/dom"], function(dom){
    dom.byId("someNode").innerHTML = "Hello World";
});

If you pass byId a domNode reference, the same node is returned:

require(["dojo/dom"], function(dom){
    var node = dom.byId("someNode");
    var other = dom.byId(node);
    console.log(node == other);
});

// output
>>> true

If you pass 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:

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!");
  }
});

Most (if not all) functions in Dojo accept either a string or DomNode as a parameter. If passed a string, the function typically calls byId(), ensuring a domNode is always the object. For instance:

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);
});

The latter is preferred, as the call to 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:

require(["dojo/dom"], functiom(dom)){
  var othernode = dom.byId("fallbackNode");
  var node = dom.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.

Arguments

Argument Type Description
id String The id of the DOM node to be returned

Examples

The following example lets a node by id disappear from the screen.

This example uses some of the basic libraries of dojo/on and dojo/_base/fx in addition to dojo/dom.

require(["dojo/dom", "dojo/on", "dojo/_base/fx", "dojo/domReady!"],
function(dom, on, baseFx){
  var node = dom.byId("findMe");
  on(dom.byId("buttonOne"), "click", function(){
    baseFx.fadeOut({ node: node, duration: 300 }).play();
  });
  on(dom.byId("buttonTwo"), "click", function(){
    baseFx.fadeIn({ node: node, duration: 300 }).play();
  })
});

Some basic HTML to facilitate the example.

<button id="buttonOne">Hide Me!</button> <button id="buttonTwo">Show Me!</button>
<div id="findMe">Hiya!</div>

And some CSS styling so we can see what we are doing...

#findMe {
  width: 200px;
  height: 100px;
  background: #f3f3f3;
  border: 1px dotted #ccc;
  color: #444;
  padding: 10px;
  margin: 10px;
}

isDescendant()

Returns true if node is a descendant of ancestor.

Usage

require(["dojo/dom"], function(dom){
  dom.isDescendant("someNode", "someOtherNode");
});

Arguments

Argument Type Description
node DomNode|String The node you want to check is a descendant
ancestor DomNode|String The node you think might be the ancestor

Examples

Code that checks if two nodes are descended from a third.

require(["dojo/dom", "dojo/domReady!"], function(dom){
  var output = "";
  if (dom.isDescendant("child", "ancestor")){
    output += "'child' is a descendant of 'ancestor'</br>";
  }else{
    output += "'child' is not a descendant of 'ancestor'</br>";
  }
  if (dom.isDescendant("loner", "ancestor")){
    output += "'loner' is a descendant of 'ancestor'</br>";
  }else{
    output += "'loner' is not a descendant of 'ancestor'</br>";
  }
  dom.byId("output").innerHTML = output;
});

Some basic HTML to facilitate the example.

<div id="ancestor">
  <div id="child">I'm a child!</div>
</div>
<div id="loner">I'm not a child!</div>
<div id="output"></div>

setSelectable()

Enable or disable selection on a node

Usage

require(["dojo/dom"], function(dom){
  dom.setSelectable("someNode", true);
});

Arguments

Argument Type Description
node DomNode|String The node you want to set selection on
selectable Boolean True if selectable or false if not

Examples

An example of how to set a node to selectable or not.

Code using dojo/on to set the click handlers of two buttons to allow the ability to turn selectable on and off.

require(["dojo/dom", "dojo/on", "dojo/domReady!"], function(dom, on){
  on(dom.byId("button1"), "click", function(){
    dom.setSelectable("model", true);
  });
  on(dom.byId("button2"), "click", function(){
    dom.setSelectable("model", false);
  });
});

Some basic HTML to facilitate the example.

<div id="model">Am I selectable?</div>
<button id="button1">setSelectable True</button>
<button id="button2">setSelectable False</button>

See also