medium-to-markdown/node_modules/collapse-whitespace/lib/whitespace.js

137 lines
3.1 KiB
JavaScript

'use strict';
var voidElements = require('void-elements');
Object.keys(voidElements).forEach(function (name) {
voidElements[name.toUpperCase()] = 1;
});
var blockElements = {};
require('block-elements').forEach(function (name) {
blockElements[name.toUpperCase()] = 1;
});
/**
* isBlockElem(node) determines if the given node is a block element.
*
* @param {Node} node
* @return {Boolean}
*/
function isBlockElem(node) {
return !!(node && blockElements[node.nodeName]);
}
/**
* isVoid(node) determines if the given node is a void element.
*
* @param {Node} node
* @return {Boolean}
*/
function isVoid(node) {
return !!(node && voidElements[node.nodeName]);
}
/**
* whitespace(elem [, isBlock]) removes extraneous whitespace from an
* the given element. The function isBlock may optionally be passed in
* to determine whether or not an element is a block element; if none
* is provided, defaults to using the list of block elements provided
* by the `block-elements` module.
*
* @param {Node} elem
* @param {Function} blockTest
*/
function collapseWhitespace(elem, isBlock) {
if (!elem.firstChild || elem.nodeName === 'PRE') return;
if (typeof isBlock !== 'function') {
isBlock = isBlockElem;
}
var prevText = null;
var prevVoid = false;
var prev = null;
var node = next(prev, elem);
while (node !== elem) {
if (node.nodeType === 3) {
// Node.TEXT_NODE
var text = node.data.replace(/[ \r\n\t]+/g, ' ');
if ((!prevText || / $/.test(prevText.data)) && !prevVoid && text[0] === ' ') {
text = text.substr(1);
}
// `text` might be empty at this point.
if (!text) {
node = remove(node);
continue;
}
node.data = text;
prevText = node;
} else if (node.nodeType === 1) {
// Node.ELEMENT_NODE
if (isBlock(node) || node.nodeName === 'BR') {
if (prevText) {
prevText.data = prevText.data.replace(/ $/, '');
}
prevText = null;
prevVoid = false;
} else if (isVoid(node)) {
// Avoid trimming space around non-block, non-BR void elements.
prevText = null;
prevVoid = true;
}
} else {
node = remove(node);
continue;
}
var nextNode = next(prev, node);
prev = node;
node = nextNode;
}
if (prevText) {
prevText.data = prevText.data.replace(/ $/, '');
if (!prevText.data) {
remove(prevText);
}
}
}
/**
* remove(node) removes the given node from the DOM and returns the
* next node in the sequence.
*
* @param {Node} node
* @return {Node} node
*/
function remove(node) {
var next = node.nextSibling || node.parentNode;
node.parentNode.removeChild(node);
return next;
}
/**
* next(prev, current) returns the next node in the sequence, given the
* current and previous nodes.
*
* @param {Node} prev
* @param {Node} current
* @return {Node}
*/
function next(prev, current) {
if (prev && prev.parentNode === current || current.nodeName === 'PRE') {
return current.nextSibling || current.parentNode;
}
return current.firstChild || current.nextSibling || current.parentNode;
}
module.exports = collapseWhitespace;