Get caret position in HTML input?
How do I get the index of the tex开发者_运维百科t caret in an input?
-> selectionStart
<!doctype html>
<html>
<head>
<meta charset = "utf-8">
<script type = "text/javascript">
window.addEventListener ("load", function () {
var input = document.getElementsByTagName ("input");
input[0].addEventListener ("keydown", function () {
alert ("Caret position: " + this.selectionStart);
// You can also set the caret: this.selectionStart = 2;
});
});
</script>
<title>Test</title>
</head>
<body>
<input type = "text">
</body>
</html>
The following will get you the start and end of the selection as character indices. It works for text inputs and textareas, and is slightly complicated because of IE's strange handling of line breaks.
function getInputSelection(el) {
var start = 0, end = 0, normalizedValue, range,
textInputRange, len, endRange;
if (typeof el.selectionStart == "number" && typeof el.selectionEnd == "number") {
start = el.selectionStart;
end = el.selectionEnd;
} else {
range = document.selection.createRange();
if (range && range.parentElement() == el) {
len = el.value.length;
normalizedValue = el.value.replace(/\r\n/g, "\n");
// Create a working TextRange that lives only in the input
textInputRange = el.createTextRange();
textInputRange.moveToBookmark(range.getBookmark());
// Check if the start and end of the selection are at the very end
// of the input, since moveStart/moveEnd doesn't return what we want
// in those cases
endRange = el.createTextRange();
endRange.collapse(false);
if (textInputRange.compareEndPoints("StartToEnd", endRange) > -1) {
start = end = len;
} else {
start = -textInputRange.moveStart("character", -len);
start += normalizedValue.slice(0, start).split("\n").length - 1;
if (textInputRange.compareEndPoints("EndToEnd", endRange) > -1) {
end = len;
} else {
end = -textInputRange.moveEnd("character", -len);
end += normalizedValue.slice(0, end).split("\n").length - 1;
}
}
}
}
return {
start: start,
end: end
};
}
var textBox = document.getElementById("textBoxId");
textBox.focus();
alert( getInputSelection(textBox).start );
There is now a nice jQuery plugin for this: Caret plugin
Then you can just call $("#myTextBox").caret();
We had used something like this for an old javascript application, but I haven't tested it in a couple years:
function getCaretPos(input) {
// Internet Explorer Caret Position (TextArea)
if (document.selection && document.selection.createRange) {
var range = document.selection.createRange();
var bookmark = range.getBookmark();
var caret_pos = bookmark.charCodeAt(2) - 2;
} else {
// Firefox Caret Position (TextArea)
if (input.setSelectionRange)
var caret_pos = input.selectionStart;
}
return caret_pos;
}
Get coordinates (css: left:x , top:y) of the current caret position in order to position an element (e.g. show tooltip at caret position)
function getCaretCoordinates() {
let x = 0,
y = 0;
const isSupported = typeof window.getSelection !== "undefined";
if (isSupported) {
const selection = window.getSelection();
// Check if there is a selection (i.e. cursor in place)
if (selection.rangeCount !== 0) {
// Clone the range
const range = selection.getRangeAt(0).cloneRange();
// Collapse the range to the start, so there are not multiple chars selected
range.collapse(true);
// getCientRects returns all the positioning information we need
const rect = range.getClientRects()[0];
if (rect) {
x = rect.left; // since the caret is only 1px wide, left == right
y = rect.top; // top edge of the caret
}
}
}
return { x, y };
}
demo: https://codesandbox.io/s/caret-coordinates-index-contenteditable-9tq3o?from-embed
ref: https://javascript.plainenglish.io/how-to-find-the-caret-inside-a-contenteditable-element-955a5ad9bf81
Working example of getting cursor point in text box:
function textbox()
{
var ctl = document.getElementById('Javascript_example');
var startPos = ctl.selectionStart;
var endPos = ctl.selectionEnd;
alert(startPos + ", " + endPos);
}
加载中,请稍侯......
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