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Simple Duck Punching Example in Vanilla JavaScript
// Duck Punching in JavaScript
const sentence = 'The quick brown fox jumps over the lazy dog. If the dog barked, was it really lazy?';
const legacyIndexOf = String.prototype.indexOf;
// Extending the indexOf functionality to return the last occurence of the searchValue
String.prototype.indexOf = function (searchValue, fromIndex, getLastIndexFlag = false) {
if (!getLastIndexFlag) {
return, searchValue, fromIndex);
} else {
return' ').reverse().join(' '), searchValue, fromIndex);
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