Analyzing Text

Modern JS allows you to easily search for text parts inside a string without complex regular expressions.

1. Modern Methods (True/False)

str.includes(substr): Was a match found?
str.startsWith(substr): Does the string start with this?
str.endsWith(substr): Does it end with this?

2. Good Old indexOf

Returns the POSITION (index) of the first match or -1 if nothing is found.

let str = "Moo";
alert( str.indexOf("oo") ); // 1 (0-based indexing: M=0, o=1, o=2)

Caution

Case matters! Searching for includes("Widget") will not find the word "widget". Always coerce to the same case before searching if exact matching isn't critical.

Tip

All these methods have a second argument — the starting position for the search. For example, str.includes("a", 5) will start searching for " a " only from the 5th character.