javascript - 对 'this' 的内部引用未在返回对象中解析

Question

这个问题已经有答案了:

Self-references in object literals / initializers (31 个回答)

已关闭 8 年前。

我正在尝试构造一个返回对象。为了避免逻辑重复，某些要素取决于其他要素。当我尝试使用“这个”时。引用已创建的项目，它无法解析。

function calcNextYear(lastYear) {
    return {
        age : lastYear.age + 1,
        earnings : calcEarnings(lastYear.earnings,this.age),
        savings :  calcSavings(lastYear.endingAmount),
        investmentIncome : calcInvestmentIncome(lastYear.endingAmount,this.age),
        spending : calcSpending(this.age),
        net : this.savings + this.investmentIncome - this.spending,
        endingAmount : start.savingsAmount + this.net
    }
}

未呈现的项目为 Netty 和期末金额。 “start”是一个现有对象。

Answer 1

这不是this的工作方式；您不能引用对象字面量中的先前值。你最好使用变量:

function calcNextYear(lastYear) {
    var age = lastYear.age + 1;
    var savings = calcSavings(lastYear.endingAmount);
    var spending = calcSpending(age);
    var investmentIncome = calcInvestmentIncome(lastYear.endingAmount, age);
    var net = savings + investmentIncome - spending;
    return {
        age : age,
        earnings : calcEarnings(lastYear.earnings, age),
        savings :  savings,
        investmentIncome : investmentIncome,
        spending : spending,
        net : net,
        endingAmount : start.savingsAmount + net
    }
}