Beginner level · Module 1: JavaScript Setup and Basics · Lesson 3 of 3
Operators, Strings and Template Literals
Calculate with arithmetic operators, build readable text with template literals and use common string methods.
In this lesson you will
- Use arithmetic and comparison operators
- Build text with template literals and string methods
Key concepts
arithmetic operatorstemplate literals `${}`toFixed and toLocaleStringstring methods
The lesson
JavaScript has the usual operators: + - * /, % for the remainder and ** for powers. Decimal arithmetic can produce tiny rounding errors such as 0.1 + 0.2 = 0.30000000000000004; for money, work in whole units such as SSP or cents and format the result for display.
Template literals use backticks and ${} to insert values: `Total: ${total} SSP`. They are clearer than joining strings with + and can span several lines.
Strings have useful methods: toUpperCase(), trim(), includes(), slice(), replace() and padStart(). Numbers can be formatted with toFixed(2) or toLocaleString("en-US") for thousands separators.
Step by step
- Calculate the cost of 3 items at 3,500 SSP.
- Print it in a template literal with toLocaleString.
- Trim and capitalise a messy name.
- Calculate a 15% discount and format it with toFixed(2).
Practice activity
Complete the data-bundle comparison activity, printing one formatted sentence per offer with the cost per GB.
Expected result: Each offer prints a clear sentence with the correct cost per GB to two decimal places.
Check your understanding
-
How do you insert a variable into a template literal?
Show answer
With ${variable} inside a backtick string.
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Why is 0.1 + 0.2 not exactly 0.3?
Show answer
Decimal fractions are stored in binary floating point, which cannot represent them exactly.
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