| 1 | ;
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| 2 | module.exports = function (arr, predicate, ctx) {
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| 3 | if (typeof Array.prototype.findIndex === 'function') {
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| 4 | return arr.findIndex(predicate, ctx);
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| 5 | }
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| 6 |
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| 7 | if (typeof predicate !== 'function') {
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| 8 | throw new TypeError('predicate must be a function');
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| 9 | }
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| 10 |
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| 11 | var list = Object(arr);
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| 12 | var len = list.length;
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| 13 |
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| 14 | if (len === 0) {
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| 15 | return -1;
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| 16 | }
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| 17 |
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| 18 | for (var i = 0; i < len; i++) {
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| 19 | if (predicate.call(ctx, list[i], i, list)) {
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| 20 | return i;
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| 21 | }
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| 22 | }
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| 23 |
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| 24 | return -1;
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| 25 | };
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