Analysis and Solution to the Javascript floating point operation _ javascript skills

JavaScript has only one numeric type Number, and all numbers in Javascript are represented in IEEE-754 standard format. The precision of floating point numbers is not unique to JavaScript, because some decimal places indicate that the digits are infinite decimal binary digits.
0.1 0.0001 1001 1001 1001...
0.2 0.0011 0011 0011 0011...
0.3 0.0100 1100 1100 1100...
0.4 0.0110 0110 0110 0110...
0.5 0.1
0.6 0.1001 1001 1001 1001...
Therefore, for example, in 1.1, the program cannot really represent '1. 1', but can only be accurate to a certain extent. This is an unavoidable loss of precision:

1.09999999999999999
The problem in JavaScript is more complicated. Here we only give some test data in Chrome:

Input and Output
1.0-0.9 = 0.1 False
1.0-0.8 = 0.2 False
1.0-0.7 = 0.3 False
1.0-0.6 = 0.4 True
1.0-0.5 = 0.5 True
1.0-0.4 = 0.6 True
1.0-0.3 = 0.7 True
1.0-0.2 = 0.8 True
1.0-0.1 = 0.9 True
Solution
How can we avoid this type of 1.0-0.9! = What happens to 0.1 of non-bug issues? The following provides a more widely used solution. The accuracy of the computing result is reduced before the floating point calculation result is judged, because the accuracy is automatically rounded down:

The Code is as follows:

(1.0-0.9). toFixed (digits) // The toFixed () precision parameter must be between 0 and 20
ParseFloat (1.0-0.9). toFixed (10) === 0.1 // The result is True.
ParseFloat (1.0-0.8). toFixed (10) === 0.2 // The result is True.
ParseFloat (1.0-0.7). toFixed (10) === 0.3 // The result is True.
ParseFloat (11.0-11.8). toFixed (10) ===- 0.8 // The result is True.

Method Extraction

The Code is as follows:

// Use the isEqual tool to determine whether the values are equal
Function isEqual (number1, number2, digits ){
Digits = undefined? 10: digits; // The default precision is 10.
Return number1.toFixed (digits) === number2.toFixed (digits );
}

IsEqual (1.0-0.7, 0.3); // return true

// Native extension method, prefer the object-oriented Style
Number. prototype. isEqual = function (number, digits ){
Digits = undefined? 10: digits; // The default precision is 10.
Return this. toFixed (digits) === number. toFixed (digits );
}

(1.0-0.7). isEqual (0.3); // return true