17 I like Pablo's answer, but Array#indexOf and Array#map don't work on all browsers. Underscore will use native code if it's available, but has fallbacks as well. Plus it has the pluck method for doing …

Jan 3, 2017 · I am confused between the difference between the two function indexOf and find Index in an array. The documentation says findIndex - Returns the index of the first element in the array where

Dec 9, 2008 · If your situation requires the use of a regular expression, use the search() method, otherwise; the indexOf() method is more performant.

Dec 21, 2011 · I am learning Javascript and don't understand why the indexOf below returns -1: var string = "The quick brown fox jumps over the lazy dog"; console.log (string.indexOf("good"));

10 This kind of function doesn't exist built in, but it would be pretty easy to make it yourself. Thankfully, indexOf can also accept a starting index as the second parameter.

Dec 20, 2017 · 1 indexOf returns a -1 if the search is not in the string. This is because indexOf will return the position of the search term in the string. For example > -1 is another way of saying !== -1 though …

Jan 1, 2022 · The indexOf function of a string does not return a character but rather returns the position of the first place that string or character is found, not the character itself.

.indexOf() and .includes() methods can be used to search for an element in an array or to search for a character/substring in a given string. Usage in Array (Link to ECMAScript Specification) indexOf uses …

Apr 14, 2013 · var numberList = [100,200,300,400,500]; var index = numberList.indexOf(200); // 1 You will get -1 if it cannot find a value in the array.

Dec 27, 2013 · The .indexOf() method has an optional second parameter that specifies the index to start searching from, so you can call it in a loop to find all instances of a particular value: