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Jeff Lange
8,788 PointsUsing indexOf - how does it know where to look?
In JavaScript strings we just wrote this code:
var part1 = "Hello ";
var part2 = "World!";
var whole = part1 + part2;
console.log(whole);
console.log(whole + "!!!!");
var length = whole.length;
console.log(whole.length)
var index = whole.indexOf("World");
console.log(index);
var index2 = whole.indexOf("world");
console.log(index2);
if (whole.indexOf("W") !== -1){
console.log("W exists in string")
} else {
console.log("W does not exist");
}
But I'm confused. How does the indexOf in the if statement know to search for the capital W in the variable "index" instead of in "index2"?
1 Answer

mikescs
5,018 PointsIt does not. It searches in variable "whole". It call indexOf method for variable whole. whole variable consists of part1 and part2 variable. Hence it searches in "Hello World".
Jeff Lange
8,788 PointsJeff Lange
8,788 PointsOhhh...right, right, right, because it's not just
indexOf
it'swhole.indexOf
.And since "whole" is made up of "Hello World!" it searches that for the uppercase "W" (which, indeed, it finds). If I changed the value of part 2 to "world" or "adslfjadlf" or whatever, the
whole.indexOf
wouldn't find a "W" so it would print the "W does not exist" console.log.That was super helpful! Thank you :)