Difference between toFixed() and toPrecision()?

toFixed(n) provides n length after the decimal point; toPrecision(x) provides x total length.

Ref at w3schools: toFixed and toPrecision

EDIT:
I learned a while back that w3schools isn't exactly the best source, but I forgot about this answer until I saw kzh's, uh, "enthusiastic" comment. Here are additional refs from Mozilla Doc Center for toFixed() and for toPrecision(). Fortunately for all of us, MDC and w3schools agree with each other in this case.

For completeness, I should mention that toFixed() is equivalent to toFixed(0) and toPrecision() just returns the original number with no formatting.

I believe that the former gives you a fixed number of decimal places, whereas the latter gives you a fixed number of significant digits.

Math.PI.toFixed(2); // "3.14"Math.PI.toPrecision(2); // "3.1"

Furthermore, toPrecision will yield scientific notation if there are more integer digits in the number than the specified precision.

(Math.PI * 10).toPrecision(2); // "31"(Math.PI * 100).toPrecision(2); // "3.1e+2"

EDIT:Oh, and if you are new to JavaScript, I can highly recommend the book "JavaScript: The Good Parts" by Douglas Crockford.

Examples speak clearly:

var A = 123.456789;A.toFixed()      // 123A.toFixed(0)     // 123A.toFixed(1)     // 123.5      round up lastA.toFixed(2)     // 123.46     round up lastA.toFixed(3)     // 123.457    round up lastA.toFixed(4)     // 123.4568   round up lastA.toFixed(5)     // 123.45679  round up lastA.toFixed(6)     // 123.456789A.toFixed(7)     // 123.4567890A.toFixed(8)     // 123.45678900A.toFixed(9)     // 123.456789000A.toFixed(10)    // 123.4567890000A.toFixed(11)    // 123.45678900000A.toPrecision()      // 123.456789 A.toPrecision(0)     // --- ERROR --- A.toPrecision(1)     // 1e+2A.toPrecision(2)     // 1.2e+2A.toPrecision(3)     // 123A.toPrecision(4)     // 123.5      round up lastA.toPrecision(5)     // 123.46     round up lastA.toPrecision(6)     // 123.457    round up lastA.toPrecision(7)     // 123.4568   round up lastA.toPrecision(8)     // 123.45679  round up lastA.toPrecision(9)     // 123.456789A.toPrecision(10)    // 123.4567890A.toPrecision(11)    // 123.45678900