locutus
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Locutus other languages' standard libraries to JavaScript for fun and educational purposes
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JavaScript
export function substr_count(haystack, needle, offset, length) {
// discuss at: https://locutus.io/php/substr_count/
// original by: Kevin van Zonneveld (https://kvz.io)
// bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
// improved by: Brett Zamir (https://brett-zamir.me)
// improved by: Thomas
// example 1: substr_count('Kevin van Zonneveld', 'e')
// returns 1: 3
// example 2: substr_count('Kevin van Zonneveld', 'K', 1)
// returns 2: 0
// example 3: substr_count('Kevin van Zonneveld', 'Z', 0, 10)
// returns 3: false
let cnt = 0;
const normalizedHaystack = String(haystack);
const normalizedNeedle = String(needle);
const normalizedOffset = Number.isNaN(Number(offset)) ? 0 : Number(offset);
const normalizedLength = Number.isNaN(Number(length)) ? 0 : Number(length);
if (normalizedNeedle.length === 0) {
return false;
}
let position = normalizedOffset - 1;
while ((position = normalizedHaystack.indexOf(normalizedNeedle, position + 1)) !== -1) {
if (normalizedLength > 0 && position + normalizedNeedle.length > normalizedLength) {
return false;
}
cnt++;
}
return cnt;
}