Any View API to get row number by an index value

[nekw]

Is there any API or quick way to get row number providing a index value from a View

E.g.
{
Field1: [k1, k2, k3, k4],
Field2: [a, b, c, d]
}
Where Field1 is index

View.GetRowNumberByIndexValue('k2')

Return 2

[texodus]

You can use a filter:

await table.view({filter: [["Field1", "==", "k2"]]});

[nekw]

How to get the value 2 from this? (2 means 2nd row here)

[texodus]

(await view.to_json())[0]

You may want to review the docs retrieving data from a View as well as the View constructor transform with interactive examples. Beyond just answering your immediate questions, there are some important details there that are specific to wasm (distinct from JavaScript), e.g. memory management.