通过JavaScript对象进行迭代

Question

无法访问对象。 它们打印为未定义。 救命！ 我需要代码来打印学生姓名。

let students = [
        {name: 'Remy', cohort: 'Jan'},
        {name: 'Genevieve', cohort: 'March'},
        {name: 'Chuck', cohort: 'Jan'},
        {name: 'Osmund', cohort: 'June'},
        {name: 'Nikki', cohort: 'June'},
        {name: 'Boris', cohort: 'June'}
    ];



    function objPrint() {
        for (var i=0; i<students.length; i++) {
           console.log("Name: " + students[i][0] + " Cohort: " + students[i][1])
        }
    }

Answer 1

您正在访问项目，就像它是一个数组。 但实际上它是一系列对象。

顶级，已经获取当前项目的项目，只需使用点或括号表示法访问键以获取值。

 let students = [ {name: 'Remy', cohort: 'Jan'}, {name: 'Genevieve', cohort: 'March'}, {name: 'Chuck', cohort: 'Jan'}, {name: 'Osmund', cohort: 'June'}, {name: 'Nikki', cohort: 'June'}, {name: 'Boris', cohort: 'June'} ]; students.forEach((item) => { //console.log(`Name - ${item.name} :: Cohort - ${item.cohort}`); console.log('Name - ' + item.name + " :: Cohort - " + item.cohort ); }); 

Answer 2

做这样的事情：

let students = [
    {name: 'Remy', cohort: 'Jan'},
    {name: 'Genevieve', cohort: 'March'},
    {name: 'Chuck', cohort: 'Jan'},
    {name: 'Osmund', cohort: 'June'},
    {name: 'Nikki', cohort: 'June'},
    {name: 'Boris', cohort: 'June'}
];



function objPrint() {
    for (var i=0; i<students.length; i++) {
       // Can also use students[i]['name'] , students[i]['cohort']
       // using lodash.js _.get(students, [i, 'name'], 'default value');
       // using new destructuring let {name, cohort} = students[i] then console.log("name: "+ name + " Cohort: "+cohort);
       console.log("Name: " + students[i].name + " Cohort: " + students[i].cohort);
    }
}

Answer 3

您需要像这样调用键/属性： students[i].name然后使用方法objPrint()来打印值。

 let students = [ {name: 'Remy', cohort: 'Jan'}, {name: 'Genevieve', cohort: 'March'}, {name: 'Chuck', cohort: 'Jan'}, {name: 'Osmund', cohort: 'June'}, {name: 'Nikki', cohort: 'June'}, {name: 'Boris', cohort: 'June'} ]; function objPrint() { for (var i=0; i<students.length; i++) { console.log("Name: " + students[i].name + " Cohort: " + students[i].cohort) } } objPrint(); 

Answer 4

对象的属性可通过点表示法访问，而不是带数字的括号。 所以你应该这样做

students[i].name

Answer 5

试试..of：

 let students = [ {name: 'Remy', cohort: 'Jan'}, {name: 'Genevieve', cohort: 'March'}, {name: 'Chuck', cohort: 'Jan'}, {name: 'Osmund', cohort: 'June'}, {name: 'Nikki', cohort: 'June'}, {name: 'Boris', cohort: 'June'} ] // returns an object as a student for(let student of students) { console.log(`Name: ${student.name} Cohort: ${student.cohort}`) } 

因此你可以访问对象的属性，你可以做任何事情。

这种方法的好处

• 与.foreach()不同，它适用于break，continue和return
• 它避免了for-in的所有陷阱（使用索引而不是对象）

并且..使用反引号来避免旧式的字符串连接方式 - 它看起来更好:)

Answer 6

尝试这个：

let students = [
        {name: 'Remy', cohort: 'Jan'},
        {name: 'Genevieve', cohort: 'March'},
        {name: 'Chuck', cohort: 'Jan'},
        {name: 'Osmund', cohort: 'June'},
        {name: 'Nikki', cohort: 'June'},
        {name: 'Boris', cohort: 'June'}
    ];

function sobjPrint() {
  for (var i in students) {

    if (students.hasOwnProperty(i)) {
       console.log("Name: " + students[i].name + " Cohort: " + students[i].cohort)
    }
  }
}