property 'length' does not exist on type 'childnode' in javascript

When you receive the error "Property 'length' does not exist on type 'ChildNode'" in TypeScript, it means that you are trying to access the length property on an object of type ChildNode which does not have a length property.

One way to handle this issue is to first check if the object is an instance of the expected type before accessing the length property. Here is an example:

index.ts
const nodes = document.querySelectorAll('.my-class');
if (nodes && nodes instanceof NodeListOf<ChildNode>) {
  const length = nodes.length;
  // Do something with the length here
}
181 chars
6 lines

In this code block, we first ensure that the nodes variable is not null or undefined, and that it is an instance of NodeListOf<ChildNode>. Once this condition is met, we can safely access the length property on the nodes object.

Alternatively, if you do not need strict type checking, you can cast the object to any to avoid TypeScript checking:

index.ts
const nodes = document.querySelectorAll('.my-class');
const length = (<any>nodes).length;
// Do something with the length here
127 chars
4 lines

However, it is generally recommended to avoid casting to any if possible, as this can lead to type errors at runtime.