1.发现使用频率较高但尚未被定义的函数;

2.找到和验证函数的基础算法;

3.定义函数的变量;

4.考虑特殊和极端情况下的结果;

5.以代码形式呈现;

6.通过测试用例测试有效性;

7.提交文档.

下面以阶乘n!为例

1.发现没有现成的阶乘函数

2.算法: n! = n*(n-1)*(n-2).....*1

3.定义函数变量为n

4.当n 为 0 或1 时 n! = 1

5.在xlsx-calc/formulajs/lib/financial.js目录下,以代码实现(

exports.factorial = function (n){
    if(n <= 1) {
         return 1;      
    }
    else{
          return n * factorial(n-1);   
    }
}

6.在xlsx-calc/tests/test.js目录下建立测试用例,测试成功.

var formulajs = require('../formulajs/index');
var XLSX_CALC = require('../index');
var assert = require('assert');
describe('formulajs integration', function() {  describe('XLSX_CALC.import_functions()', function() {
it('FACTORIAL', function() {
      XLSX_CALC.import_functions(formulajs);
      var workbook = {};
      workbook.Sheets = {};
      workbook.Sheets.Sheet1 = {};
      workbook.Sheets.Sheet1.C835 = {v: 10};
      workbook.Sheets.Sheet1.H845 = {f: '=FACTORIAL(C835)'};
      XLSX_CALC(workbook);
      console.log(workbook.Sheets.Sheet1.H845.v);
      assert.equal(workbook.Sheets.Sheet1.H845.v, 3628800);
    });
  });
});