Function findIndex

Like Array.findIndex but with optional startAt and length parameters to limit the search to a specific section of the array.

const data = ["red","blue","red","blue"]
data.findIndex(v => v === `red`); // 0 - finds first match
findIndex(data, v => v === `red`, 1); // 2 - finds first match after start index of 1
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Use findIndexReverse to search backwards through the array.