/**
* @license
* Copyright The Closure Library Authors.
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @fileoverview Utilities for working with selections in input boxes and text
* areas.
*
* @see ../demos/dom_selection.html
*/
goog.provide('goog.dom.selection');
goog.require('goog.dom.InputType');
goog.require('goog.string');
/**
* Sets the place where the selection should start inside a textarea or a text
* input
* @param {Element} textfield A textarea or text input.
* @param {number} pos The position to set the start of the selection at.
*/
goog.dom.selection.setStart = function(textfield, pos) {
'use strict';
if (goog.dom.selection.useSelectionProperties_(textfield)) {
textfield.selectionStart = pos;
}
};
/**
* Return the place where the selection starts inside a textarea or a text
* input
* @param {Element} textfield A textarea or text input.
* @return {number} The position where the selection starts or 0 if it was
* unable to find the position or no selection exists. Note that we can't
* reliably tell the difference between an element that has no selection and
* one where it starts at 0.
*/
goog.dom.selection.getStart = function(textfield) {
'use strict';
return goog.dom.selection.getEndPoints_(textfield, true)[0];
};
/**
* Returns the start and end points of the selection within a textarea in IE.
* IE treats newline characters as \r\n characters, and we need to check for
* these characters at the edge of our selection, to ensure that we return the
* right cursor position.
* @param {TextRange} range Complete range object, e.g., "Hello\r\n".
* @param {TextRange} selRange Selected range object.
* @param {boolean} getOnlyStart Value indicating if only start
* cursor position is to be returned. In IE, obtaining the end position
* involves extra work, hence we have this parameter for calls which need
* only start position.
* @return {!Array<number>} An array with the start and end positions where the
* selection starts and ends or [0,0] if it was unable to find the
* positions or no selection exists. Note that we can't reliably tell the
* difference between an element that has no selection and one where
* it starts and ends at 0. If getOnlyStart was true, we return
* -1 as end offset.
* @private
*/
goog.dom.selection.getEndPointsTextareaIe_ = function(
range, selRange, getOnlyStart) {
'use strict';
// Create a duplicate of the selected range object to perform our actions
// against. Example of selectionRange = "" (assuming that the cursor is
// just after the \r\n combination)
var selectionRange = selRange.duplicate();
// Text before the selection start, e.g.,"Hello" (notice how range.text
// excludes the \r\n sequence)
var beforeSelectionText = range.text;
// Text before the selection start, e.g., "Hello" (this will later include
// the \r\n sequences also)
var untrimmedBeforeSelectionText = beforeSelectionText;
// Text within the selection , e.g. "" assuming that the cursor is just after
// the \r\n combination.
var selectionText = selectionRange.text;
// Text within the selection, e.g., "" (this will later include the \r\n
// sequences also)
var untrimmedSelectionText = selectionText;
// Boolean indicating whether we are done dealing with the text before the
// selection's beginning.
var isRangeEndTrimmed = false;
// Go over the range until it becomes a 0-lengthed range or until the range
// text starts changing when we move the end back by one character.
// If after moving the end back by one character, the text remains the same,
// then we need to add a "\r\n" at the end to get the actual text.
while (!isRangeEndTrimmed) {
if (range.compareEndPoints('StartToEnd', range) == 0) {
isRangeEndTrimmed = true;
} else {
range.moveEnd('character', -1);
if (range.text == beforeSelectionText) {
// If the start position of the cursor was after a \r\n string,
// we would skip over it in one go with the moveEnd call, but
// range.text will still show "Hello" (because of the IE range.text
// bug) - this implies that we should add a \r\n to our
// untrimmedBeforeSelectionText string.
untrimmedBeforeSelectionText += '\r\n';
} else {
isRangeEndTrimmed = true;
}
}
}
if (getOnlyStart) {
// We return -1 as end, since the caller is only interested in the start
// value.
return [untrimmedBeforeSelectionText.length, -1];
}
// Boolean indicating whether we are done dealing with the text inside the
// selection.
var isSelectionRangeEndTrimmed = false;
// Go over the selected range until it becomes a 0-lengthed range or until
// the range text starts changing when we move the end back by one character.
// If after moving the end back by one character, the text remains the same,
// then we need to add a "\r\n" at the end to get the actual text.
while (!isSelectionRangeEndTrimmed) {
if (selectionRange.compareEndPoints('StartToEnd', selectionRange) == 0) {
isSelectionRangeEndTrimmed = true;
} else {
selectionRange.moveEnd('character', -1);
if (selectionRange.text == selectionText) {
// If the selection was not empty, and the end point of the selection
// was just after a \r\n, we would have skipped it in one go with the
// moveEnd call, and this implies that we should add a \r\n to the
// untrimmedSelectionText string.
untrimmedSelectionText += '\r\n';
} else {
isSelectionRangeEndTrimmed = true;
}
}
}
return [
untrimmedBeforeSelectionText.length,
untrimmedBeforeSelectionText.length + untrimmedSelectionText.length
];
};
/**
* Returns the start and end points of the selection inside a textarea or a
* text input.
* @param {Element} textfield A textarea or text input.
* @return {!Array<number>} An array with the start and end positions where the
* selection starts and ends or [0,0] if it was unable to find the
* positions or no selection exists. Note that we can't reliably tell the
* difference between an element that has no selection and one where
* it starts and ends at 0.
*/
goog.dom.selection.getEndPoints = function(textfield) {
'use strict';
return goog.dom.selection.getEndPoints_(textfield, false);
};
/**
* Returns the start and end points of the selection inside a textarea or a
* text input.
* @param {Element} textfield A textarea or text input.
* @param {boolean} getOnlyStart Value indicating if only start
* cursor position is to be returned. In IE, obtaining the end position
* involves extra work, hence we have this parameter. In FF, there is not
* much extra effort involved.
* @return {!Array<number>} An array with the start and end positions where the
* selection starts and ends or [0,0] if it was unable to find the
* positions or no selection exists. Note that we can't reliably tell the
* difference between an element that has no selection and one where
* it starts and ends at 0. If getOnlyStart was true, we return
* -1 as end offset.
* @private
*/
goog.dom.selection.getEndPoints_ = function(textfield, getOnlyStart) {
'use strict';
textfield = /** @type {!HTMLInputElement|!HTMLTextAreaElement} */ (textfield);
var startPos = 0;
var endPos = 0;
if (goog.dom.selection.useSelectionProperties_(textfield)) {
startPos = textfield.selectionStart;
endPos = getOnlyStart ? -1 : textfield.selectionEnd;
}
return [startPos, endPos];
};
/**
* Sets the place where the selection should end inside a text area or a text
* input
* @param {Element} textfield A textarea or text input.
* @param {number} pos The position to end the selection at.
*/
goog.dom.selection.setEnd = function(textfield, pos) {
'use strict';
if (goog.dom.selection.useSelectionProperties_(textfield)) {
textfield.selectionEnd = pos;
}
};
/**
* Returns the place where the selection ends inside a textarea or a text input
* @param {Element} textfield A textarea or text input.
* @return {number} The position where the selection ends or 0 if it was
* unable to find the position or no selection exists.
*/
goog.dom.selection.getEnd = function(textfield) {
'use strict';
return goog.dom.selection.getEndPoints_(textfield, false)[1];
};
/**
* Sets the cursor position within a textfield.
* @param {Element} textfield A textarea or text input.
* @param {number} pos The position within the text field.
*/
goog.dom.selection.setCursorPosition = function(textfield, pos) {
'use strict';
if (goog.dom.selection.useSelectionProperties_(textfield)) {
// Mozilla directly supports this
textfield.selectionStart = pos;
textfield.selectionEnd = pos;
}
};
/**
* Sets the selected text inside a textarea or a text input
* @param {Element} textfield A textarea or text input.
* @param {string} text The text to change the selection to.
*/
goog.dom.selection.setText = function(textfield, text) {
'use strict';
textfield = /** @type {!HTMLInputElement|!HTMLTextAreaElement} */ (textfield);
if (goog.dom.selection.useSelectionProperties_(textfield)) {
var value = textfield.value;
var oldSelectionStart = textfield.selectionStart;
var before = value.substr(0, oldSelectionStart);
var after = value.substr(textfield.selectionEnd);
textfield.value = before + text + after;
textfield.selectionStart = oldSelectionStart;
textfield.selectionEnd = oldSelectionStart + text.length;
} else {
throw new Error('Cannot set the selection end');
}
};
/**
* Returns the selected text inside a textarea or a text input
* @param {Element} textfield A textarea or text input.
* @return {string} The selected text.
*/
goog.dom.selection.getText = function(textfield) {
'use strict';
textfield = /** @type {!HTMLInputElement|!HTMLTextAreaElement} */ (textfield);
if (goog.dom.selection.useSelectionProperties_(textfield)) {
var s = textfield.value;
return s.substring(textfield.selectionStart, textfield.selectionEnd);
}
throw new Error('Cannot get the selection text');
};
/**
* Returns the selected text within a textarea in IE.
* IE treats newline characters as \r\n characters, and we need to check for
* these characters at the edge of our selection, to ensure that we return the
* right string.
* @param {TextRange} selRange Selected range object.
* @return {string} Selected text in the textarea.
* @private
*/
goog.dom.selection.getSelectionRangeText_ = function(selRange) {
'use strict';
// Create a duplicate of the selected range object to perform our actions
// against. Suppose the text in the textarea is "Hello\r\nWorld" and the
// selection encompasses the "o\r\n" bit, initial selectionRange will be "o"
// (assuming that the cursor is just after the \r\n combination)
var selectionRange = selRange.duplicate();
// Text within the selection , e.g. "o" assuming that the cursor is just after
// the \r\n combination.
var selectionText = selectionRange.text;
// Text within the selection, e.g., "o" (this will later include the \r\n
// sequences also)
var untrimmedSelectionText = selectionText;
// Boolean indicating whether we are done dealing with the text inside the
// selection.
var isSelectionRangeEndTrimmed = false;
// Go over the selected range until it becomes a 0-lengthed range or until
// the range text starts changing when we move the end back by one character.
// If after moving the end back by one character, the text remains the same,
// then we need to add a "\r\n" at the end to get the actual text.
while (!isSelectionRangeEndTrimmed) {
if (selectionRange.compareEndPoints('StartToEnd', selectionRange) == 0) {
isSelectionRangeEndTrimmed = true;
} else {
selectionRange.moveEnd('character', -1);
if (selectionRange.text == selectionText) {
// If the selection was not empty, and the end point of the selection
// was just after a \r\n, we would have skipped it in one go with the
// moveEnd call, and this implies that we should add a \r\n to the
// untrimmedSelectionText string.
untrimmedSelectionText += '\r\n';
} else {
isSelectionRangeEndTrimmed = true;
}
}
}
return untrimmedSelectionText;
};
/**
* Helper function for returning the range for an object as well as the
* selection range
* @private
* @param {Element} el The element to get the range for.
* @return {!Array<TextRange>} Range of object and selection range in two
* element array.
*/
goog.dom.selection.getRangeIe_ = function(el) {
'use strict';
var doc = el.ownerDocument || el.document;
var selectionRange = doc.selection.createRange();
// el.createTextRange() doesn't work on textareas
var range;
if (/** @type {?} */ (el).type == goog.dom.InputType.TEXTAREA) {
range = doc.body.createTextRange();
range.moveToElementText(el);
} else {
range = el.createTextRange();
}
return [range, selectionRange];
};
/**
* Helper function for canonicalizing a position inside a textfield in IE.
* Deals with the issue that \r\n counts as 2 characters, but
* move('character', n) passes over both characters in one move.
* @private
* @param {Element} textfield The text element.
* @param {number} pos The position desired in that element.
* @return {number} The canonicalized position that will work properly with
* move('character', pos).
*/
goog.dom.selection.canonicalizePositionIe_ = function(textfield, pos) {
'use strict';
textfield = /** @type {!HTMLTextAreaElement} */ (textfield);
if (textfield.type == goog.dom.InputType.TEXTAREA) {
// We do this only for textarea because it is the only one which can
// have a \r\n (input cannot have this).
var value = textfield.value.substring(0, pos);
pos = goog.string.canonicalizeNewlines(value).length;
}
return pos;
};
/**
* Helper function to determine whether it's okay to use
* selectionStart/selectionEnd.
*
* @param {Element} el The element to check for.
* @return {boolean} Whether it's okay to use the selectionStart and
* selectionEnd properties on `el`.
* @private
*/
goog.dom.selection.useSelectionProperties_ = function(el) {
'use strict';
try {
return typeof el.selectionStart == 'number';
} catch (e) {
// Firefox throws an exception if you try to access selectionStart
// on an element with display: none.
return false;
}
};
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