Develop Reference

How to simulate the backspace key being pressed in JavaScript or jQuery

I have spent an hour reading a million different posts and can't get a winner.
Simply put. I have created an on-screen keyboard.
When a user presses a letter button, the letter is inserted at the carat in the input that has focus.
This all works fine and I know how to insert all the letters and numbers and spaces but I can't figure out how to backspace at the carat. I know how to take the last character off but that is not effective as I wish it to backspace at the carat.
I will insert the code to show how it is set up... The only part that does not work is the lines in the if ($(this).html() == 'BKSP') block.
PLEASE and THANKS!
function insertAtCursor(myField, myValue) {
//IE support
if (document.selection) {
myField.focus();
sel = document.selection.createRange();
sel.text = myValue;
}
//MOZILLA and others
else if (myField.selectionStart || myField.selectionStart == '0') {
var startPos = myField.selectionStart;
var endPos = myField.selectionEnd;
myField.value = myField.value.substring(0, startPos)
+ myValue
+ myField.value.substring(endPos, myField.value.length);
myField.selectionStart = startPos + myValue.length;
myField.selectionEnd = startPos + myValue.length;
} else {
myField.value += myValue;
}
}
$("#keyboard").on("pointerdown", function(e){
e.preventDefault();
});
$(".sm-kb-btn").on("pointerdown", function (e) {
if ($(this).html() == 'BKSP') {
var e = new Event("keydown");
e.key = "Backspace";
e.code = "Backspace";
document.getElementById("search-box-input").dispatchEvent(e);
}
else {
insertAtCursor(document.getElementById("search-box-input"), $(this).html());
}
})

The browser and javascript have limits when it comes to accessing to device hardware, for sercurity reasons. You can throw a keydown event, but it won't perform the same action as physically pressing a key.
If you're goal is just maintaining the caret position, you can set that using selection.setSelectionRange(caret_position, caret_position)
https://developer.mozilla.org/en-US/docs/Web/API/Selection
Set keyboard caret position in html textbox
Here's a demo:
let output = document.querySelector('input');
document.querySelector('.buttons').addEventListener('click', function(e){
if (e.target.nodeName === 'BUTTON') {
let caret_position = output.selectionStart || 0, //current caret position
character = e.target.textContent, //button / key pressed
new_caret_position = Math.max(0, caret_position + (character === 'BKSP' ? -1 : 1));
//if BKSP, move caret -1, else move caret +1. also make sure it's >= 0
if (character === 'BKSP'){ //remove character preceding current caret position
output.value = output.value.substr(0, new_caret_position) + output.value.substr(caret_position);
} else { //insert character at current character position
output.value = output.value.substr(0, caret_position) + character + output.value.substr(caret_position);
}
//reset the caret position after modifying output.value
output.setSelectionRange(new_caret_position, new_caret_position);
}
});
button{
height: 24px;
margin: 16px 4px;
}
<input>
<div class="buttons">
<button>Q</button>
<button>W</button>
<button>E</button>
<button>R</button>
<button>T</button>
<button>Y</button>
<button>BKSP</button>
</div>

Html selection all it works. but it throws error when select with `space`

I am doing a selection, and on highlight i adding a space. when user select the same span, i console the message.
all working fine. but when i select a existing node element (strong) with space, i am getting an error as The Range has partially selected a non-Text node.
how to solve this?
here is my code :
var currentTarget = null;
function selHTML() {
var nNd = document.createElement("span");
var w = getSelection().getRangeAt(0);
var text = window.getSelection().toString();
currentTarget = $(w.startContainer).parent();
//console.log(selection.anchorNode.baseURI);//nextElementSibling/anchorNode
if(!$(w.startContainer).parent().prop('class')) {
if($.trim(text).length < 5 ) {
console.log("Your selection is too short..!");
return;
}
try {
w.surroundContents(nNd);
currentTarget.find('span.highlight').contents().unwrap();
$(nNd).addClass('highlight');
} catch (ex) {
console.log("The Range has partially selected a non-Text node.")
}
} else {
console.log("already selected");
}
}
$("#addText").on('click', function(event) {
event.preventDefault();
$(selHTML());
});
$("button").click(function(){
$(selHTML());
});
$("#clearSpan").click(function(){
console.log($(currentTarget))
});
$("div.content").mouseup(function(event) {
var range = window.getSelection().getRangeAt(0);
if (!range.collapsed) {
var bounds = range.getBoundingClientRect();
var x = bounds.left + ((bounds.right - bounds.left - $(".savetooltipAll").outerWidth()) / 2);
var y = bounds.top - $(".savetooltipAll").outerHeight() + $(window).scrollTop();
$(".savetooltipAll").css("top", (y+(bounds.top*3)) + 'px');
$(".savetooltipAll").css("left",x + 'px');
$(".savetooltipAll").show();
} else {
$(".savetooltipAll").hide();
}
});
Demo

Highlight selected text on a page when spanning multiple non text nodes:
Highlight selected text on a page when spanning multiple non text nodes

Insert text at current cursor position on dropdown list changed inside iframe

I am using a text editor provided by Microsoft ajax-toolkit.
It renders iframe on browser. I have added a dropdown in that editor and I want that when user changes the drop-down index the value should be added in the editor current cursor position.
I got a code on SO which gives me the current selected text inside editor is as follows
function getIframeSelectionText(iframe) {
var win = iframe.contentWindow;
var doc = iframe.contentDocument || win.document;
if (win.getSelection) {
return win.getSelection().toString();
} else if (doc.selection && doc.selection.createRange) {
return doc.selection.createRange().text;
}
}
But I want to add some text at the current position. The html is rendering as below
<td class="ajax__htmleditor_editor_editpanel"><div id="Editor1_ctl02" style="height:100%;width:100%;">
<iframe id="Editor1_ctl02_ctl00" name="Editor1_ctl02_ctl00" marginheight="0" marginwidth="0" frameborder="0" style="height:100%;width:100%;display:none;border-width:0px;">
</iframe><textarea id="Editor1_ctl02_ctl01" class="ajax__htmleditor_htmlpanel_default" style="height:100%;width:100%;display:none;"></textarea><iframe id="Editor1_ctl02_ctl02" name="Editor1_ctl02_ctl02" marginheight="0" marginwidth="0" frameborder="0" style="height:100%;width:100%;display:none;border-width:0px;">
</iframe>
</div></td>
I am trying as follow
$("#imgDropdown").change(function () {
//var iframeBody = $(window.Editor1_ctl02_ctl00.document.getElementsByTagName("body")[0]);
var iframe = document.getElementById("Editor1_ctl02_ctl00");
$("#Editor1_ctl02_ctl00").find("body").insertAtCaret("value");
//alert(getIframeSelectionText(iframe));
});
the function for inserting text is not working with iframe is as follow
$.fn.extend({
insertAtCaret: function (myValue) {
if (document.selection) {
this.focus();
sel = document.selection.createRange();
sel.text = myValue;
this.focus();
}
else if (this.selectionStart || this.selectionStart == '0') {
var startPos = this.selectionStart;
var endPos = this.selectionEnd;
var scrollTop = this.scrollTop;
this.value = this.value.substring(0, startPos) + myValue + this.value.substring(endPos, this.value.length);
this.focus();
this.selectionStart = startPos + myValue.length;
this.selectionEnd = startPos + myValue.length;
this.scrollTop = scrollTop;
} else {
this.value += myValue;
this.focus();
}
}
})

Easy, you just have to use.
$("#Editor1_ctl02_ctl00").contents().find('textarea').insertAtCaret('value');
Updated
Sorry, I thought the insertAtCaret function is working for you, you just needed to work inside iFrame. You can use this version of insertAtCaret:
jQuery.fn.extend({
insertAtCaret: function (html) {
var winObject = function (el){
var doc = el.ownerDocument;
return doc.defaultView || doc.parentWindow
};
return this.each(function (i) {
var sel, range, w = this;
w = winObject(w);
if (w.getSelection) {
// IE9 and non-IE
sel = w.getSelection();
if (sel.getRangeAt && sel.rangeCount) {
range = sel.getRangeAt(0);
range.deleteContents();
// Range.createContextualFragment() would be useful here but is
// only relatively recently standardized and is not supported in
// some browsers (IE9, for one)
var el = w.document.createElement("div");
el.innerHTML = html;
var frag = w.document.createDocumentFragment(), node, lastNode;
while ((node = el.firstChild)) {
lastNode = frag.appendChild(node);
}
range.insertNode(frag);
// Preserve the selection
if (lastNode) {
range = range.cloneRange();
range.setStartAfter(lastNode);
range.collapse(true);
sel.removeAllRanges();
sel.addRange(range);
}
}
} else if (w.document.selection && w.document.selection.type != "Control") {
// IE < 9
w.document.selection.createRange().pasteHTML(html);
}
}
)
}
});
and call it like:
$("#Editor1_ctl02_ctl00").contents().find('body').insertAtCaret($val);
Function adapted from here
Happy coding!

There seem to be a few issues here.
The Microsoft ajax-toolkit editor creates an iframe where the designMode property is turned on, and that's why it's editable, it has no value, and textNodes are added straight to the body, which makes it a little more difficult.
When you're selecting something from a dropdown, the focus is on the dropdown, and there is no caret position, as the focus is shifted away from the iFrame.
I'm assuming that the dropdown is in the top menubar for the editor or anywhere else that is outside the iFrame.
Also, the Microsoft ajax-toolkit editor has a recommended update, the HTMLEditorExtender.
The code you have to capture the caret position seems to be for a regular input / textarea, and you'd have to adapt that code to work with any Node inside an iframe that is in designMode, with it's own window and document etc.
Given the above considerations, this is what I came up with to do this
var frameID = 'Editor1_ctl02_ctl00',
selectID = 'imgDropdown',
iframe = document.getElementById(frameID),
iWin = iframe.contentWindow ? iframe.contentWindow : window.frames[frameID];
$(iWin).on('blur', function() {
$(iframe).data('range', getRange(iWin));
});
$('#' + selectID).on('change', function() {
var range = $(iframe).data('range');
addText(iWin, range, this.value);
});
function getRange(win) {
var sel, range, html;
if (win.getSelection) {
sel = win.getSelection();
if (sel.getRangeAt && sel.rangeCount) {
range = sel.getRangeAt(0);
range.deleteContents();
}
} else if (win.document.selection && win.document.selection.createRange) {
range = win.document.selection.createRange();
}
return range;
}
function addText(win, range, text) {
if (win.getSelection) {
range.insertNode(win.document.createTextNode(text));
} else if (win.document.selection && win.document.selection.createRange) {
range.text = text;
}
}
FIDDLE

JavaScript: Scroll to selection after using textarea.setSelectionRange in Chrome

A JavaScript function selects a certain word in a textarea using .setSelectionRange().
In Firefox, the textarea automatically scrolls down to show the selected text. In Chrome (v14), it does not. Is there a way to get Chrome to scroll the textarea down to the newly selected text?
jQuery solutions are welcome.

Here is a simple and efficient solution in pure JavaScript:
// Get the textarea
var textArea = document.getElementById('myTextArea');
// Define your selection
var selectionStart = 50;
var selectionEnd = 60;
textArea.setSelectionRange(selectionStart, selectionEnd);
// Mow let’s do some math.
// We need the number of characters in a row
var charsPerRow = textArea.cols;
// We need to know at which row our selection starts
var selectionRow = (selectionStart - (selectionStart % charsPerRow)) / charsPerRow;
// We need to scroll to this row but scrolls are in pixels,
// so we need to know a row's height, in pixels
var lineHeight = textArea.clientHeight / textArea.rows;
// Scroll!!
textArea.scrollTop = lineHeight * selectionRow;
Put this in a function, extend the prototype of JavaScript's Element object with it, and you're good.

A lot of answers, but the accepted one doesn't consider line breaks, Matthew Flaschen didn't add the solution code, and naXa answer has a mistake. The simplest solution code is:
textArea.focus();
const fullText = textArea.value;
textArea.value = fullText.substring(0, selectionEnd);
textArea.scrollTop = textArea.scrollHeight;
textArea.value = fullText;
textArea.setSelectionRange(selectionStart, selectionEnd);

You can see how we solved the problem in ProveIt (see highlightLengthAtIndex). Basically, the trick is to truncate the textarea, scroll to the end, then restore the second part of the text. We also used the textSelection plugin for consistent cross-browser behavior.

Valeriy Katkov's elegant solution works great but has two problems:
It does not work for long strings
Selected contents are scrolled to the bottom of the textarea, making it hard to see the context which surrounds the selection
Here's my improved version that works for long strings (tested with at least 50,000 words) and scroll selection to the center of the textarea:
function setSelectionRange(textarea, selectionStart, selectionEnd) {
// First scroll selection region to view
const fullText = textarea.value;
textarea.value = fullText.substring(0, selectionEnd);
// For some unknown reason, you must store the scollHeight to a variable
// before setting the textarea value. Otherwise it won't work for long strings
const scrollHeight = textarea.scrollHeight
textarea.value = fullText;
let scrollTop = scrollHeight;
const textareaHeight = textarea.clientHeight;
if (scrollTop > textareaHeight){
// scroll selection to center of textarea
scrollTop -= textareaHeight / 2;
} else{
scrollTop = 0;
}
textarea.scrollTop = scrollTop;
// Continue to set selection range
textarea.setSelectionRange(selectionStart, selectionEnd);
}
It works in Chrome 72, Firefox 65, Opera 58, and Edge 42.
For an example of using this function, see my GitHub project SmartTextarea.

This is a code inspired by the Matthew Flaschen's answer.
/**
* Scroll textarea to position.
*
* #param {HTMLInputElement} textarea
* #param {Number} position
*/
function scrollTo(textarea, position) {
if (!textarea) { return; }
if (position < 0) { return; }
var body = textarea.value;
if (body) {
textarea.value = body.substring(0, position);
textarea.scrollTop = position;
textarea.value = body;
}
}
Basically, the trick is to truncate the textarea, scroll to the end, then restore the second part of the text.
Use it as follows
var textarea, start, end;
/* ... */
scrollTo(textarea, end);
textarea.focus();
textarea.setSelectionRange(start, end);

Based on the idea from naXa and Valeriy Katkov, I refined the function with fewer bugs. It should work out of the box (It's written with TypeScript. For JavaScript, just remove the type declaration):
function scrollTo(textarea: HTMLTextAreaElement, offset: number) {
const txt = textarea.value;
if (offset >= txt.length || offset < 0)
return;
// Important, so that scrollHeight will be adjusted
textarea.scrollTop = 0;
textarea.value = txt.substring(0, offset);
const height = textarea.scrollHeight;
textarea.value = txt;
// Margin between selection and top of viewport
textarea.scrollTop = height - 40;
}
Usage:
let textarea, start, end;
/* ... */
scrollTo(textarea, start);
textarea.focus();
textarea.setSelectionRange(start, end);

Complete code for Chrome:
<script type="text/javascript">
var SAR = {};
SAR.find = function () {
debugger;
var parola_cercata = $("#text_box_1").val(); // The searched word
// Make text lowercase if search is
// supposed to be case insensitive
var txt = $('#remarks').val().toLowerCase();
parola_cercata = parola_cercata.toLowerCase();
// Take the position of the word in the text
var posi = jQuery('#remarks').getCursorPosEnd();
var termPos = txt.indexOf(parola_cercata, posi);
if (termPos !== -1) {
debugger;
var target = document.getElementById("remarks");
var parola_cercata2 = $("#text_box_1").val();
// Select the textarea and the word
if (target.setSelectionRange) {
if ('selectionStart' in target) {
target.selectionStart = termPos;
target.selectionEnd = termPos;
this.selectionStart = this.selectionEnd = target.value.indexOf(parola_cercata2);
target.blur();
target.focus();
target.setSelectionRange(termPos, termPos + parola_cercata.length);
}
} else {
var r = target.createTextRange();
r.collapse(true);
r.moveEnd('character', termPos + parola_cercata);
r.moveStart('character', termPos);
r.select();
}
} else {
// Not found from cursor pos, so start from beginning
termPos = txt.indexOf(parola_cercata);
if (termPos !== -1) {
var target = document.getElementById("remarks");
var parola_cercata2 = $("#text_box_1").val();
// Select the textarea and the word
if (target.setSelectionRange) {
if ('selectionStart' in target) {
target.selectionStart = termPos;
target.selectionEnd = termPos;
this.selectionStart = this.selectionEnd = target.value.indexOf(parola_cercata2);
target.blur();
target.focus();
target.setSelectionRange(termPos, termPos + parola_cercata.length);
}
} else {
var r = target.createTextRange();
r.collapse(true);
r.moveEnd('character', termPos + parola_cercata);
r.moveStart('character', termPos);
r.select();
}
} else {
alert("not found");
}
}
};
$.fn.getCursorPosEnd = function () {
var pos = 0;
var input = this.get(0);
// IE support
if (document.selection) {
input.focus();
var sel = document.selection.createRange();
pos = sel.text.length;
}
// Firefox support
else if (input.selectionStart || input.selectionStart === '0')
pos = input.selectionEnd;
return pos;
};
</script>

I published an answer here:
http://blog.blupixelit.eu/scroll-textarea-to-selected-word-using-javascript-jquery/
It works perfectly with just one needed rule: Set a line-height in the CSS content of the textarea!
It calculate the position of the word to scroll to just by doing some simple mathematical calculation and it worked perfectly in all my experiments!

How to insert text at the current caret position in a textarea

On a function call from an image, I am trying to insert the alt tag value from the image into the textarea at the position where the caret currently is.
This is the code that I currently have which inserts the alt tag value to the end of the text area.
$("#emoticons").children().children().click(function () {
var ch = $(this).attr("alt");
$("#txtPost").append(ch);
});
The 2 things I have been having a problem with is determining the position of the caret, and creating a new string with the value of the textarea before the carets positon + the code I'm inserting + the value of the textarea after the carets position.

i've currently got this extension in place:
$.fn.insertAtCaret = function(text) {
return this.each(function() {
if (document.selection && this.tagName == 'TEXTAREA') {
//IE textarea support
this.focus();
sel = document.selection.createRange();
sel.text = text;
this.focus();
} else if (this.selectionStart || this.selectionStart == '0') {
//MOZILLA/NETSCAPE support
startPos = this.selectionStart;
endPos = this.selectionEnd;
scrollTop = this.scrollTop;
this.value = this.value.substring(0, startPos) + text + this.value.substring(endPos, this.value.length);
this.focus();
this.selectionStart = startPos + text.length;
this.selectionEnd = startPos + text.length;
this.scrollTop = scrollTop;
} else {
// IE input[type=text] and other browsers
this.value += text;
this.focus();
this.value = this.value; // forces cursor to end
}
});
};
and you can use it like so:
$("#txtPost").insertAtCaret(ch);