What happens when javascript operation precision is lost?

When writing JavaScript code, we are likely to encounter the problem of loss of calculation accuracy. When faced with this situation, you need to understand its causes and take appropriate measures.

First of all, we need to know that JavaScript uses the IEEE 754 standard floating point type to represent numbers. This type of memory has a fixed range of numbers that can be represented and their precision. Since the precision of the floating-point number type is fixed, precision loss may occur when the operation result exceeds its range.

For example, when operating on larger numbers, the decimal part behind may be omitted, resulting in inaccurate results. In turn, when operating on smaller numbers, rounding errors may occur, causing the results to be inaccurate as well.

When we perform floating point operations, we need to pay attention to the following points:

1. Try to avoid using decimal operations.
2. You can use integer types to perform operations, and then convert the results to floating point types.
3. Reduce the precision error that may occur in floating point operations as much as possible, for example, use the toFixed method.

The following is a simple example:

let total = 0.1 + 0.2; // 结果应该是 0.3
console.log(total); // 输出 0.30000000000000004

In this example, we use floating point operations to calculate the sum of 0.1 and 0.2, but the output result is 0.30000000000000004. This is because 0.1 and 0.2 are both infinitely recurring decimals, and the floating point type can only represent a limited number of numbers accurately. Therefore, floating-point types will represent these numbers approximately to the nearest finite number, causing problems with loss of precision.

In order to solve this problem, we can use the toFixed method to round the output result to a few decimal places, for example:

let total = 0.1 + 0.2; // 结果应该是 0.3
console.log(total.toFixed(1)); // 输出 0.3

Use the toFixed method to truncate the sum to a few decimal places. , so that the output is the correct result. Therefore, when writing JavaScript programs, we should minimize the use of floating point operations and use the toFixed method when necessary to avoid the problem of precision loss. .

In short, we need to understand the internal representation of JavaScript floating point number types and pay attention to avoid loss of precision when writing code. Sometimes, we need to use some special techniques to avoid this problem, such as using integer types to perform operations and then converting the results to floating point types. No matter which method is used, we must always pay attention to accuracy issues when writing code to ensure the correctness of the code.

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