在javascript中创建一个累积总和数组 [英] Creating an array of cumulative sum in javascript

问题描述

这是我需要做的一个例子:

This is an example of what I need to do:

var myarray = [5, 10, 3, 2];

var result1 = myarray[0];
var result2 = myarray[1] + myarray[0];
var result3 = myarray[2] + myarray[1] + myarray[0];
var result4 = myarray[3] + myarray[2] + myarray[1] + myarray[0];

所以所有这些都会输出 5, 15, 18, 20

so all that would output 5, 15, 18, 20

但不是像那样写出所有的变量，我希望它说:

but instead of writing out all the vars like that, I want it to say something like:

var result = arrayitem + the sum of any previous items 

有意义吗?那可能吗?我怎么做?

Does that make sense? Is that possible? How do I do that?

推荐答案

从 Nina Scholz 复制的优雅解决方案，使用柯里化以访问先前的值.

An elegant solution copied from Nina Scholz, using currying to access the previous value.

const cumulativeSum = (sum => value => sum += value)(0);

console.log([5, 10, 3, 2].map(cumulativeSum));

cumulativeSum 是函数 value =>sum += value，sum 初始化为零.每次调用时，sum 都会更新，并在下次调用时(输入 [n])等于前一个值 (output[n-1]).

cumulativeSum is the function value => sum += value, with sum initialized to zero. Every time it's called, sum is updated and will equal the previous value (output[n-1]) when called the next time (with input[n]).

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