Converting between strings, numbers and booleans.
✍️ 3 exercises + code challenge in this lessonValues can be converted explicitly:
Number("3.5"), parseInt(), parseFloat(), or unary plus +"3"String(42) or (42).toString()Boolean(value) or !!valueJavaScript also converts types automatically, sometimes surprisingly: "5" + 2 is "52" (string joining) but "5" - 2 is 3.
Mastering JavaScript Type Conversion helps you write clean and reliable JavaScript code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
<pre id="out"></pre>
<script>
const log = (...a) => document.getElementById("out").textContent += a.join(" ") + "\n";
log(Number("3.5") + 1);
log(+"10" + 5);
log(String(42) + 8);
log(!!"hello", !!0);
log('"5" + 2 =', "5" + 2);
log('"5" - 2 =', "5" - 2);
log('"5" * "2" =', "5" * "2");
log("Number('abc') =", Number("abc"));
</script>Check what you learned in “JavaScript Type Conversion”.
Convert the number to a string.
const text = (42);
What is "5" + 2?
Convert "3.5" with parseFloat, multiply by 2 and log it.
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