I'm working with a project that has this crazy for loop to expand nodes in a D3.js canvas interactive. Essentially, what I want is to expand all children. So if an object has a child, I want to expand them.
I cut out a chunk of code from this. There's so many for loops it's ridiculous. How can I reduce this to a simple "find all children, preform toggle(); and update();"?
$('.expandAll').click(function(e) {
e.preventDefault();
length = root.children.length;
for (var i = 0; i < length; i++) {
toggle(root.children[i]);
update(root);
if (root.children[i]['children']) {
childlength = root.children[i]['children'].length;
for (var j = 0; j < childlength; j++) {
toggle(root.children[i]['children'][j]);
update(root);
if (root.children[i]['children'][j]['children']) {
childlength2 = root.children[i]['children'][j]['children'].length;
for (var k = 0; k < childlength2; k++) {
toggle(root.children[i]['children'][j]['children'][k]);
update(root);
}
}
}
}
}
});
Sounds like a good case for recursion:
$('.expandAll').click(function(e) {
e.preventDefault();
expandAll(root);
});
var expandAll = function (node) {
toggle(node);
update(node);
// edit: if nodes with no children are lacking the children property
if (!node.children) {
return;
}
for (var i = 0, length = node.children.length; i < length; i++) {
expandAll(node.children[i]);
}
};
I'm not sure what toggle and update exactly means, but you may be able to perform just a single top-level update call after calling expandAll(root);.
Not sure if this will help, but something I've been doing with nested objects:
object = {
children: [], // array of similar objects with children property and update function
update: function(data){
// update this item
this.data = data;
// update each immediate child
if (this.children)
for (var i in this.children)
this.children[i].update(data);
}
};
// then you just call update on the first item:
object.update(data);
If you follow this pattern, rather than setting up complex loops at the root level, you simply loop through the immediate children and call their update function, which then loops through their children, and goes all the way down.
I'm not a great JS developer, just something I was doing for some nested comments I was working with the other day ;)
Use recursion! If you need to support only three levels, you can introduce a counter variable for that.
$('.expandAll').click(function(e) {
e.preventDefault();
expandAll(root, root.children/*, 3*/);
}
function expandAll(root, children/*, lev*/) {
if (!children/* || lev<=0 */) return;
var length = children.length;
for (var i = 0; i < length; i++) {
toggle(children[i]);
update(root);
expandAll(root, children[i].children/*, lev-1*/);
}
}
Btw, are you sure that you need to call update on the root after every single toggle? It would make more sense to me to call it once in the end when all children are toggled.
Related
I have a for loop that suddenly stops working when I try to push to an array. The best way to describe what's going on is just to show my code and try an explain what's going on.
for (var i = 0; i < childs.length; i++) {
if (childs[i].length > 0) {
for (var j = 0; j < amountsValue[i].options.custValues.length; j++) {
var label = amountsValue[i].options.custValues[j].label;
var value = amountsValue[i].options.custValues[j].value;
for (var k = childs[i].length - 1; k >= 0; k--) {
if (childs[i][k].attributes[label] != value) {
childBackup.push(childs[i][k]);
childs[i].splice(k, 1);
}
}
}
amountsValue[i].id = childs[i][0].attributes.internalid;
childs.push(childBackup);
}
}
What's happening is I am looping through an array of items which may or may not have custom options available such as different sizes or colours. The loop will check to see if there are any then get the value and label from the array.
After this, we then loop again to try and match up the values with option values stored within a separate model. The plan is to check if the value is the same as the one stored and if not then splice it from the array. The process of elimination should eventually leave only one option left and that will be used to get the internalid.
During this a back up of the spliced objects is kept so that they can be appended to the array again so that the user can change the option they want. The problem is using childs.push(childBackup) stops the browser form reading the options on amountsValue. This works if the code is removed or it is pushed into another index so I'm really not sure why it isn't working.
Does anyone have any suggestions on how to get this working? I'm sorry if this doesn't make much sense, I've tried to explain it as best I can but let me know if anything needs to be cleared up.
EDIT: I have fixed the issue. Thank you to everyone who suggested ways to solve the problem. As others said, I was trying to manipulate the array I was looping through and changing the length on it. So that part of the code was taken outside the loop and after the initial loop another loop was set up which contained the following code:
for (var i = 0; i < childBackup.length; i++) {
childs[0].push(childBackup[i]);
}
It now works as intended. Thank you.
You are manipulating the array you are looping through.
var count = childs.length;
for (var i = 0; i < count; i++) {
if (childs[i].length > 0) {
for (var j = 0; j < amountsValue[i].options.custValues.length; j++) {
var label = amountsValue[i].options.custValues[j].label;
var value = amountsValue[i].options.custValues[j].value;
for (var k = childs[i].length - 1; k >= 0; k--) {
if (childs[i][k].attributes[label] != value) {
childBackup.push(childs[i][k]);
childs[i].splice(k, 1);
}
}
}
amountsValue[i].id = childs[i][0].attributes.internalid;
childs.push(childBackup);
}
}
I'm very new at recursion, and have been tasked with writing getElementsByClassName in JavaScript without libraries or the DOM API.
There are two matching classes, one of which is in the body tag itself, the other is in a p tag.
The code I wrote isn't working, and there must be a better way to do this. Your insight would be greatly appreciated.
var elemByClass = function(className) {
var result = [];
var nodes = document.body; //<body> is a node w/className, it needs to check itself.
var childNodes = document.body.childNodes; //then there's a <p> w/className
var goFetchClass = function(nodes) {
for (var i = 0; i <= nodes; i++) { // check the parent
if (nodes.classList == className) {
result.push(i);
console.log(result);
}
for (var j = 0; j <= childNodes; j++) { // check the children
if (childNodes.classList == className) {
result.push(j);
console.log(result);
}
goFetchClass(nodes); // recursion for childNodes
}
goFetchClass(nodes); // recursion for nodes (body)
}
return result;
};
};
There are some errors, mostly logical, in your code, here's what it should have looked like
var elemByClass = function(className) {
var result = [];
var pattern = new RegExp("(^|\\s)" + className + "(\\s|$)");
(function goFetchClass(nodes) {
for (var i = 0; i < nodes.length; i++) {
if ( pattern.test(nodes[i].className) ) {
result.push(nodes[i]);
}
goFetchClass(nodes[i].children);
}
})([document.body]);
return result;
};
Note the use of a regex instead of classList, as it makes no sense to use classList which is IE10+ to polyfill getElementsByClassName
Firstly, you'd start with the body, and check it's className property.
Then you'd get the children, not the childNodes as the latter includes text-nodes and comments, which can't have classes.
To recursively call the function, you'd pass the children in, and do the same with them, check for a class, get the children of the children, and call the function again, until there are no more children.
Here are some reasons:
goFetchClass needs an initial call after you've defined it - for example, you need a return goFetchClass(nodes) statement at the end of elemByClass function
the line for (var i = 0; i <= nodes; i++) { will not enter the for loop - did you mean i <= nodes.length ?
nodes.classList will return an array of classNames, so a direct equality such as nodes.classList == className will not work. A contains method is better.
Lastly, you may want to reconsider having 2 for loops for the parent and children. Why not have 1 for loop and then call goFetchClass on the children? such as, goFetchClass(nodes[i])?
Hope this helps.
I am trying to delete an element based on string match for a object property but when I do a slice on the javascript array the array size decreases and indexes change. Please help e with a solution. Here is a jsfiddle link for the same.
Code
var selection = JSON.parse('[{"Connectors":"c1"},{"Connectors":"c2"},{"Schedules":"s1"},{"Schedules":"s2"},{"Gauges":"g1"},{"Gauges":"g2"},{"Gauges":"g3"}]');
removeitem("Gauges");
function removeitem(item) {
for (var i = 0; i < selection.length; i++) {
if (selection[i].hasOwnProperty(item)) {
selection.splice(i, 1);
}
}
}
Add i--;
function removeitem(item) {
for (var i = 0; i < selection.length; i++) {
if (selection[i].hasOwnProperty(item)) {
selection.splice(i, 1);
i--;
}
}
}
jsfiddle example
Assuming you don't have a problem with having undefined as the new value, then you could call delete[i]; instead of selection.splice(i, 1); in that case the length does not change and neither will the indices.
Both Abhi1964 and Loolooii solution seems to work fine and solve problem, but i would personally keep the filtered results in separate array instead of manipulating index/deleting value in the same array, reason being, separate array would make code look simpler to read and understand. Reviewer need not to understand the index manipulation or keep track of undefined.
var selection = JSON.parse('[{"Connectors":"c1"},{"Connectors":"c2"},{"Schedules":"s1"},{"Schedules":"s2"},{"Gauges":"g1"},{"Gauges":"g2"},{"Gauges":"g3"}]');
removeitem("Gauges");
var filteredResult = [];
function removeitem(item) {
for (var i = 0; i < selection.length; i++) {
if (selection[i].hasOwnProperty(item)) {
}else{
filteredResult.push(item);
}
}
}
//use filtered result as per your need.
Note:
I have not run this code, if some error seems to be there, please feel free to edit.
I want to scan a div for all childNodes including the ones that are nestled within other elements. Right now I have this:
var t = document.getElementById('DivId').childNodes;
for(i=0; i<t.length; i++) alert(t[i].id);
But it only gets the children of the Div and not the grandchildren. Thanks!
Edit: This question was too vague. Sorry about that. Here's a fiddle:
http://jsfiddle.net/F6L2B/
The body.onload script doesn't run at JSFiddle, but it works, except that the 'Me Second' and 'Me Third' input fields are not being assigned a tabIndex and are therefore being skipped over.
This is the fastest and simplest way, and it works on all browsers:
myDiv.getElementsByTagName("*")
If you're looking for all HTMLElement on modern browsers you can use:
myDiv.querySelectorAll("*")
What about great-grandchildren?
To go arbitrarily deep, you could use a recursive function.
var alldescendants = [];
var t = document.getElementById('DivId').childNodes;
for(let i = 0; i < t.length; i++)
if (t[i].nodeType == 1)
recurseAndAdd(t[i], alldescendants);
function recurseAndAdd(el, descendants) {
descendants.push(el.id);
var children = el.childNodes;
for(let i=0; i < children.length; i++) {
if (children[i].nodeType == 1) {
recurseAndAdd(children[i]);
}
}
}
If you really only want grandchildren, then you could take out the recursion (and probably rename the function)
function recurseAndAdd(el, descendants) {
descendants.push(el.id);
var children = el.childNodes;
for(i=0; i < children.length; i++) {
if (children[i].nodeType == 1) {
descendants.push(children[i].id);
}
}
}
If anyone else wants all nodes within that tree, and not just the elements, here's a 2022-era JS snippet:
function getDescendantNodes(node, all = []) {
all.push(...node.childNodes);
for (const child of node.childNodes)
getDescendantNodes(child, all);
return all;
}
Protip: afterwards, you can filter to your preferred nodeType with the Node global: nodes = getDescendantNodes($0); nodes.filter(n => n.nodeType === Node.TEXT_NODE)
I have the following:
for (var i = 0; i < children.length; i++){
if(hasClass(children[i], "lbExclude")){
children[i].parentNode.removeChild(children[i]);
}
};
I would like it to loop through all children's children, etc (not just the top level). I found this line, which seems to do that:
for(var m = n.firstChild; m != null; m = m.nextSibling) {
But I'm unclear on how I refer to the current child if I make that switch? I would no longer have i to clarify the index position of the child. Any suggestions?
Thanks!
Update:
I'm now using the following, according to answer suggestions. Is this the correct / most efficient way of doing so?
function removeTest(child) {
if (hasClass(child, "lbExclude")) {
child.parentNode.removeChild(child);
}
}
function allDescendants(node) {
for (var i = 0; i < node.childNodes.length; i++) {
var child = node.childNodes[i];
allDescendants(child);
removeTest(child);
}
}
var children = temp.childNodes;
for (var i = 0; i < children.length; i++) {
allDescendants(children[i]);
};
function allDescendants (node) {
for (var i = 0; i < node.childNodes.length; i++) {
var child = node.childNodes[i];
allDescendants(child);
doSomethingToNode(child);
}
}
You loop over all the children, and for each element, you call the same function and have it loop over the children of that element.
Normally you'd have a function that could be called recursively on all nodes. It really depends on what you want to do to the children. If you simply want to gather all descendants, then element.getElementsByTagName may be a better option.
var all = node.getElementsByTagName('*');
for (var i = -1, l = all.length; ++i < l;) {
removeTest(all[i]);
}
There's no need for calling the 'allDescendants' method on all children, because the method itself already does that. So remove the last codeblock and I think that is a proper solution (á, not thé =])
function removeTest(child){
if(hasClass(child, "lbExclude")){
child.parentNode.removeChild(child);
}
}
function allDescendants (node) {
for (var i = 0; i < node.childNodes.length; i++) {
var child = node.childNodes[i];
allDescendants(child);
removeTest(child);
}
}
var children = allDescendants(temp);
You can use BFS to find all the elements.
function(element) {
// [].slice.call() - HTMLCollection to Array
var children = [].slice.call(element.children), found = 0;
while (children.length > found) {
children = children.concat([].slice.call(children[found].children));
found++;
}
return children;
};
This function returns all the children's children of the element.
The most clear-cut way to do it in modern browsers or with babel is this. Say you have an HTML node $node whose children you want to recurse over.
Array.prototype.forEach.call($node.querySelectorAll("*"), function(node) {
doSomethingWith(node);
});
The querySelectorAll('*') on any DOM node would give you all the child nodes of the element in a NodeList. NodeList is an array-like object, so you can use the Array.prototype.forEach.call to iterate over this list, processing each child one-by-one within the callback.
If you have jquery and you want to get all descendant elements you can use:
var all_children= $(parent_element).find('*');
Just be aware that all_children is an HTML collection and not an array. They behave similarly when you're just looping, but collection doesn't have a lot of the useful Array.prototype methods you might otherwise enjoy.
if items are being created in a loop you should leave a index via id="" data-name or some thing. You can then index them directly which will be faster for most functions such as (!-F). Works pretty well for 1024 bits x 100 items depending on what your doing.
if ( document.getElementById( cid ) ) {
return;
} else {
what you actually want
}
this will be faster in most cases once the items have already been loaded. only scrub the page on reload or secure domain transfers / logins / cors any else and your doing some thing twice.
If you use a js library it's as simple as this:
$('.lbExclude').remove();
Otherwise if you want to acquire all elements under a node you can collect them all natively:
var nodes = node.getElementsByTagName('*');
for (var i = 0; i < nodes.length; i++) {
var n = nodes[i];
if (hasClass(n, 'lbExclude')) {
node.parentNode.removeChild(node);
}
}
To get all descendants as an array, use this:
function getAllDescendants(node) {
var all = [];
getDescendants(node);
function getDescendants(node) {
for (var i = 0; i < node.childNodes.length; i++) {
var child = node.childNodes[i];
getDescendants(child);
all.push(child);
}
}
return all;
}
TreeNode node = tv.SelectedNode;
while (node.Parent != null)
{
node = node.Parent;
}
CallRecursive(node);
private void CallRecursive(TreeNode treeNode)
{
foreach (TreeNode tn in treeNode.Nodes)
{
//Write whatever code here this function recursively loops through all nodes
CallRecursive(tn);
}
}