I have the following function:
public recursiveFilterLayers(node: LayerNode[]): LayerNode[] {
const validItem = node.filter(
(i) => i.visible === true || i.visible === undefined
);
validItem.forEach((i) => {
if (i.children) i.children = this.recursiveFilterLayers(i.children);
});
return validItem;
}
And using:
data = recursiveFilterLayers(data);
How to rewrite this function to use without return like:
recursiveFilterLayers(data);
I mean pass the reference to data array.
Array.filter returns a copy, so you can't mutate the original array with it. Instead, you will need to explicitly iterate over the array using a loop.
It's tempting to use splice to remove individual values, but this has O(n²) behaviour because splice has to copy all subsequent elements one place backwards every time an element is removed.
A better approach is to keep a read and a write index, and perform a single splice at the end to cut off the end of the array:
function recursiveFilterLayers(node) {
let readIndex;
let writeIndex = 0;
for (readIndex = 0; readIndex < node.length; readIndex++) {
const element = node[readIndex];
if (element.visible === true || element.visible === undefined) {
node[writeIndex] = element;
if (element.children) {
recursiveFilterLayers(element.children);
}
writeIndex++;
}
}
node.splice(writeIndex, readIndex - writeIndex);
}
const data = [
{visible: true},
{},
{visible: false},
{
children: [{visible: false}, {visible: true}],
},
];
recursiveFilterLayers(data);
console.log(data);In javascript, primitives are passed by value, and Objects are passed by "copy of a reference". You don't have to return at all, a function can modify the content.
Although you used a filter that copies the parameter's content thus won't modify anything. Instead, we can use forEach like following.
public recursiveFilterLayers(nodes: LayerNode[]): LayerNode[] {
nodes.forEach(n=>{
if((n.visible === true || n.visible === undefined) && n.children){
this.recursiveFilterLayers(n.children);
}
});
return;
}