Javascript SyntaxError：缺少； before语句（for循环之后）

Question

我不断收到此错误，这使我感到困惑。

function calculate(){
    var n = document.getElementById("noOfCourses").value;
    for(var i = 0 ; i < n ; i++) {
        var course[i] = document.getElementById("GPA" + i+1).value;
        var hours[i] = document.getElementById("hours" + i+1).value;
        // Calculate the product of Course GPA and Credit Hours
        var product[i] = course[i] * hours[i];
    }
}

Answer 1

基本上，您需要在使用它们之前声明和初始化数组。

function calculate(){
    var n = document.getElementById("noOfCourses").value,
        course = [],  // declare and init before
        hours = [],   // declare and init before
        product = []; // declare and init before

    for(var i = 0 ; i < n ; i++) {
        course[i] = document.getElementById("GPA" + i+1).value;
        hours[i] = document.getElementById("hours" + i+1).value;
        // Calculate the product of Course GPA and Credit Hours
        product[i] = course[i] * hours[i];
    }
}

Answer 2

var关键字用于声明新变量，并可选地对其进行初始化。 在普通作业中不使用它。 而且在要声明的变量中包含索引是没有意义的-索引用于访问数组的内容，而不声明任何内容。

function calculate(){
    var n = document.getElementById("noOfCourses").value;
    for(var i = 0 ; i < n ; i++) {
        course[i] = document.getElementById("GPA" + i+1).value;
        hours[i] = document.getElementById("hours" + i+1).value;
        // Calculate the product of Course GPA and Credit Hours
        product[i] = course[i] * hours[i];
    }
}