web api instance method
Range: setStart() method
The Range.setStart() method sets the start position of a
Range.
If the startNode is a Node of type Text,
Comment, or CDataSection, then startOffset is
the number of characters from the start of startNode. For other
Node types, startOffset is the number of child nodes between
the start of the startNode.
Setting the start point below (lower in the document) the end point will result in a collapsed range with the start and end points both set to the specified start position.
Syntax
setStart(startNode, startOffset)
Parameters
startNodestartOffset- : An integer greater than or equal to zero representing the offset for the start of
the
Rangefrom the start ofstartNode.
- : An integer greater than or equal to zero representing the offset for the start of
the
Return value
None (undefined).
Examples
Highlight part of an element
This example uses the Range.setStart() and setEnd()
methods to add part of an address to a range. The selected range is then highlighted
using surroundContents().
The address contains nine nodes: five text nodes, and four <br>
elements.
HTML
<p id="address">
Wyatt Earp<br />
101 E. Main St.<br />
Dodge City, KS<br />
67801<br />
USA
</p>
<hr />
<p>Nodes in the original address:</p>
<ol id="log"></ol>
JavaScript
const address = document.getElementById("address");
const log = document.getElementById("log");
// Log info
address.childNodes.forEach((node) => {
const li = document.createElement("li");
li.textContent = `${node.nodeName}, ${node.nodeValue}`;
log.appendChild(li);
});
// Highlight the street and city
const startOffset = 2; // Start at third node: 101 E. Main St.
const endOffset = 5; // End at fifth node: Dodge City, KS
const range = document.createRange();
range.setStart(address, startOffset);
range.setEnd(address, endOffset);
const mark = document.createElement("mark");
range.surroundContents(mark);
Result
Get characters from a text node
This example uses the Range.setStart() and setEnd()
methods to define the contents of a range. The resulting range contains the first
through fifth characters within a text node.
HTML
<p id="content">0123456789</p>
<p id="log"></p>
JavaScript
const element = document.getElementById("content");
const textNode = element.childNodes[0];
const range = document.createRange();
range.setStart(textNode, 0); // Start at first character
range.setEnd(textNode, 5); // End at fifth character
document.getElementById("log").textContent = range;