I am working with a D3.js collapsible tree that contains multiple nodes. Within the tree, there are certain paths where sequences of nodes have only one child. Consider this example:
5
/
1 - 2 - 3 - 4 -6
\
7
When the 1 node is clicked, I want it to transition to become like this:
5
/
1 - 4 -6
\
7
Currently, my code allows for expanding and collapsing nodes in a normal manner. How can I identify these intermediate nodes so that I can specifically target them with my toggle function?
The structure of my code closely aligns with the provided example, with some additional customizations unrelated to this particular issue. The toggle() function takes a reference to a node as input and hides the visible child nodes (in the children array) by moving them to the _children array. While this approach applies to all children and descendants of a given node, I need it to distinguish nodes with exactly one child. Furthermore, if a node has no children, I want it to remain visible; if a node has more than one child, I want all subsequent children to be shown.
Here is the implementation of the toggle() function triggered by an onclick event on one of the nodes:
function toggle(d) {
var myLength;
if(d.children){myLength = d.children.length;}
else{myLength=0;}
if (myLength === 1) {
//next will be the first node we find with more than one child
var next = d.children[0];
for (;;) {if(next.hasOwnProperty('children')){
if (next.children.length === 1) {
next = next.children[0];
} else if (next.children.length > 1) {
break;
}
} else {
// you'll have to handle nodes with no children
break;
}
}
d._children = d.children;
d.children = [next];
}else{
if (d.children) {
d._children = d.children;
d.children = null;
} else {
d.children = d._children;
d._children = null;
}
}
}