files/en-us/web/api/htmltextareaelement/selectionstart/index.md
{{APIRef("HTML DOM")}}
The selectionStart property of the {{domxref("HTMLTextAreaElement")}} interface specifies the start position of the current text selection in a {{HTMLElement("textarea")}} element. It is a number representing the beginning index of the selected text. It can be used to both retrieve and set the start of the index of the beginning of a <textarea>s selected text.
When nothing is selected, the value of both the selectionStart and {{domxref("HTMLTextAreaElement.selectionEnd", "selectionEnd")}} is the position of the cursor (caret) inside the <textarea> element.
Setting selectionStart to a value greater than the current value of {{domxref("HTMLTextAreaElement.selectionEnd", "selectionEnd")}} updates both the selectionStart and selectionEnd properties to that value. If that value is equal to or greater than the {{domxref("HTMLTextAreaElement.textLength", "textLength")}}, both properties are both set to the textLength property value.
The property value can be retrieved and set without the <textarea> having focus, but the element does need to have focus for the {{cssxref("::selection")}} pseudo-element to match the selected text.
Setting the selectionStart to a new value fires the {{domxref("HTMLTextAreaElement.selectionchange_event", "selectionchange")}} and {{domxref("HTMLTextAreaElement.select_event", "select")}} events.
A non-negative number.
const textarea = document.getElementById("text-box");
const start = textarea.selectionStart;
{{Specifications}}
{{Compat}}