How JavaScript uses the arr.findIndex function

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Arr.findIndex: returns the subscript of the first element in the array that passes the test (judged in the function fn)

Array.prototype.findIndex = Array.prototype.findIndex | | function findIndex (fn, ctx) {ctx = ctx | | this let result; ctx.some ((value, index, arr), thisValue) = > {return fn (value, index, arr)? (result = index, true): false}) return result} Thank you for reading! This is the end of the article on "how to use the arr.findIndex function in JavaScript". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!