Why is the Math.sumPrecise method being proposed for JavaScript?

The TC39 proposal for adding a Math.sumPrecise method to JavaScript aims to address the limitations of the current Array.prototype.reduce method for summing values, particularly with floating point numbers.

This proposal, found in the advanced stages of the TC39 process (stage 2.7), suggests a significant enhancement over the naive summation method that JavaScript developers commonly use.

The proposal outlines a method to sum numbers in a way that avoids the precision errors associated with floating point arithmetic in JavaScript.

It advocates for a function that delivers the maximum possible accuracy by emulating arbitrary-precision arithmetic without actually requiring it.

The essence of this approach is detailed in the Shewchuk '96 algorithm, which has been adapted to JavaScript and expanded to handle edge cases like intermediate overflow.

The choice to name the function Math.sumPrecise rather than a simple Math.sum is deliberate, emphasizing that this method provides a higher precision alternative to straightforward summation.

This function strictly accepts numbers, rejecting non-numeric inputs, which is a departure from functions like Math.max that coerce inputs to numbers. Furthermore, the proposal specifies that the function will return -0 for an empty list to maintain consistent behavior with other JavaScript operations.

This addition would simplify code and enhance its correctness and reliability, especially in scientific and financial computing contexts where precision is paramount.

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