Determine the character's position in an input field by tracking mouse movements

Question

Determine the character's position in an input field by tracking mouse movements

I am in need of a way to determine the position of a character in an input field based on mouse movement.

For example, if the input field contains the value 'abcde' and I hover my mouse over the character 'a', the position should be 1. Similarly, hovering over 'b' should give me 2, and so on for the rest of the characters.

I have found some examples that utilize functions like selectionStart, but they only work when the caret is already at a specific position within the field.

What I really need is a solution that can track the position of the character under the mouse pointer without requiring any click action on the input field.

I have been unable to find any information on how to convert mouse coordinates into corresponding character positions using JavaScript APIs. Any suggestions or ideas would be greatly appreciated.

Update:

My ultimate goal is to automatically move the caret as the user drags over a contenteditable div. I came across a similar question on Stack Overflow, but no satisfactory solution has been provided yet.

Link to caret auto-move: https://stackoverflow.com/questions/12397792/update-caret-position-of-input-and-insert-text-on-drop-event/53660415#53660415

I have also included another example to demonstrate the difference in behavior between native drag and jQuery drag. Currently, I am using jQuery draggable, which does not support automatic caret dragging.

Link to Example on JSFiddle

javascript html jquery css selection-api

Answer 1

Answer №1

Jquery: You might want to give the Caret plugin a shot (although I can't guarantee it will meet your requirements). Further information can be found on the jquery page, although it may not be very informative!

Javascript solutions:

After searching for existing solutions, I only came across one potentially adaptable solution for hover/mouseover functionality. The code is not originally mine; I adapted it from a public fiddle by Carlos Delgado. If you hover over the "Show position" text, it will display the cursor position. Additionally, it showcases the usage of selectionStart and selectionEnd to show start and end positions when text is selected. Try this shorter version here (without start/end info).

// JavaScript function to get input selection position
function getInputSelection(el) {
  // Code implementation here...
}

// Event listener for mouseover event
document.getElementById("trigger").addEventListener("mouseover", function() {
  // Code logic here...
  
}, false);

#trigger{background:#ff8890;}

<p>
  Get the cursor position in a textarea or a text input or the selected text.
</p><br>
<textarea id="texto"></textarea><br><br>
<input type="text" id="trigger" value="Show Position" size="10" /><br><br>
<span id="result"></span>

This alternative solution might also be suitable: It displays the position in the console, which could be preferred. Feel free to adapt it as necessary.

// JavaScript code snippet for showing caret position
document.getElementById('showpos').addEventListener('mouseenter', e => {
  console.log('Caret at: ', e.target.selectionStart)
})

<input id="showpos" />

I hope these suggestions prove to be helpful!

Rachel

Answer 2

Jquery: You might want to give the Caret plugin a shot (although I can't guarantee it will meet your requirements). Further information can be found on the jquery page, although it may not be very informative!

Javascript solutions:

After searching for existing solutions, I only came across one potentially adaptable solution for hover/mouseover functionality. The code is not originally mine; I adapted it from a public fiddle by Carlos Delgado. If you hover over the "Show position" text, it will display the cursor position. Additionally, it showcases the usage of selectionStart and selectionEnd to show start and end positions when text is selected. Try this shorter version here (without start/end info).

// JavaScript function to get input selection position
function getInputSelection(el) {
  // Code implementation here...
}

// Event listener for mouseover event
document.getElementById("trigger").addEventListener("mouseover", function() {
  // Code logic here...
  
}, false);

#trigger{background:#ff8890;}

<p>
  Get the cursor position in a textarea or a text input or the selected text.
</p><br>
<textarea id="texto"></textarea><br><br>
<input type="text" id="trigger" value="Show Position" size="10" /><br><br>
<span id="result"></span>

This alternative solution might also be suitable: It displays the position in the console, which could be preferred. Feel free to adapt it as necessary.

// JavaScript code snippet for showing caret position
document.getElementById('showpos').addEventListener('mouseenter', e => {
  console.log('Caret at: ', e.target.selectionStart)
})

<input id="showpos" />

I hope these suggestions prove to be helpful!

Rachel

Answer 3

Answer №2

Below is a function that can be used with mouse move event's pageX and pageY values:

/**
 * This function retrieves the nearest caret position based on provided coordinates.
 * @param x {int}
 * @param y {int}
 * @param doc {Document}
 * @return {[Node, int]} Node containing the caret and its offset within the node. */
function findNearestCaretPosition(x, y, doc=document) {

    // For Firefox
    if (doc.caretPositionFromPoint) {
        let caretPosition = doc.caretPositionFromPoint(x, y);
        if (caretPosition)
            return [caretPosition.offsetNode, caretPosition.offset];
    }

    // For other browsers
    if (doc.caretRangeFromPoint) {
        let range = doc.caretRangeFromPoint(x, y);
        if (range)
            return [range.startContainer, range.startOffset];
    }

    return null;
}

Answer 4

Below is a function that can be used with mouse move event's pageX and pageY values:

/**
 * This function retrieves the nearest caret position based on provided coordinates.
 * @param x {int}
 * @param y {int}
 * @param doc {Document}
 * @return {[Node, int]} Node containing the caret and its offset within the node. */
function findNearestCaretPosition(x, y, doc=document) {

    // For Firefox
    if (doc.caretPositionFromPoint) {
        let caretPosition = doc.caretPositionFromPoint(x, y);
        if (caretPosition)
            return [caretPosition.offsetNode, caretPosition.offset];
    }

    // For other browsers
    if (doc.caretRangeFromPoint) {
        let range = doc.caretRangeFromPoint(x, y);
        if (range)
            return [range.startContainer, range.startOffset];
    }

    return null;
}

Determine the character's position in an input field by tracking mouse movements

Answer №1

Answer №2

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