JavaScript is one of the easiest programming languages to learn. If you are confused on how to check if one string contains another substring in JavaScript, then you have come to the right place. There are many ways one can achieve the desired result, so let’s go through them one by one.
The most common method: string.indexOf()
string.indexOf()
The best way to find a substring from a string is to use the indexOf() function. If you noticed, the indexOf() method simply tests if the substring is present or not. If it is present, it will return the starting index of the substring; if not, it will return -1. We can use the behavior of the indexOf() method to find a substring. All we need to do is set a condition to check for the return value.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 |
var programminglanguages = "C++, JavaScript, Ruby"; var newlanguage = "Python"; function findNewProgrammingLanguage(language) { if (programminglanguages.indexOf(language) >=0) { console.log(language + "is present"); } else { console.log(language + "is absent"); } } findNewProgrammingLanguage(newlanguage); |
RegExp.test() method
Next, we can use the RegExp.test() method to find a substring. This method returns a boolean and hence is much easier to use. In comparison to the indexOf() method, it returns direct true or false results and can therefore be a good alternative.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 |
var programminglanguages = "C++, JavaScript, Ruby"; var newlanguage = "Python"; function findNewProgrammingLanguage(language) { var programmingReg = new RegExp(newlanguage); if (programmingReg.test(programminglanguages)) { console.log(language + "is present"); } else { console.log(language + "is absent"); } } findNewProgrammingLanguage(newlanguage); |
String.contains()
The last method is String.contains(). It directly checks if the substring is present or not and returns a boolean value. It is available after ECMAScript 6, and hence needs to be used with caution.
Do you have anything to add to the tutorial? If yes, don’t forget to comment below and let us know.
You can also check on our website for videos about JavaScript. Below are some examples:
- Functional JavaScript (part 10) – JavaScript
- JSbroadcast.com – Hacking in MEAN Stack (part 32) – JavaScript
You can also follow some of our broadcasters who program in JavaScript as below:
TGOlson
agjsAnother cool way to find out interesting things about JavaScript is to access our project page!
