如何找到一个数组的多个索引值来调用另一个数组，javascript

Question

Here's what I've got so far. I have two arrays, I've found the conditional values of a numeric array 'grade'(grades >= 60), I'm now trying to find the index values that correspond with those array values that are >= 60, so that I may then call on these index(es) on another array 'names' to return the students 'names' who correspond to the passing grade.

Any pointers or tips greatly appreciated, thank you.

let total = 0;
let highest = 0;
let stuAvg= 0;  
let arr = [];


var names= [];
var grade= [];
var pos1 = [];



for (var i = 0; i < 10; i++) {             
    names.push(prompt('Enter The Ten Student Names | Student: ' + (i + 1))); 
    document.getElementById("stuNames").innerHTML=("Student's Names:" +names.join(','));
}
for (var i = 0; i < 10; i++) {              
    grade.push(Number(prompt('Enter The Ten Student Grades | Grade: ' + (i + 1))));
    total +=grade[i]; 
    stuAvg = total / grade.length;
    highest = Math.max(...grade);


    document.getElementById("stuGrades").innerHTML=("Student's Grades:" +grade.join(','));
}
function passing(grade) {
    return grade >= 60; 
}

function results() {
    pos1 = grade.indexOf(highest);
    arr = grade.filter(passing);


    document.getElementById("result").innerHTML=("Highest Grade:"+highest+"The Highest Grade 
          Belongs to:"+names[pos1]+" The Average Grade is "+stuAvg+"");
    document.getElementById("passing").innerHTML=("The Students who are passing are 
          "+arr+","+names+"");     
}

Answer 1

After this line:

total +=grade[i];

If it's a passing grade, add the index of that student to a passingGradeIndexes array:

if (passing(grade[i])) passingGradeIndexes.append(i);

Then output the names:

for (var i = 0; i < passingGradeIndexes.Length; i++) {
document.Write( names[passingGradeIndexes[i]] );
}

Answer 2

You can store those indexes in another array when doing the filter.

 function results() { pos1 = grade.indexOf(highest); var passingStudents = []; // to store passing indexes arr = grade.filter((grade, index) => { var pass = grade >= 60; if(pass){ passingStudents.push(index); } return pass; }); passingStudents = passingStudents.map(index => names[index]); // change indexes for names document.getElementById("result") .innerHTML=("Highest Grade:"+highest +"\\n The Highest Grade Belongs to:"+names[pos1] +"\\nThe Average Grade is "+stuAvg+""); document.getElementById("passing") .innerHTML=("The Students who are passing are: " + passingStudents.join(", ")); }

Now you have the indexes you need in another array.

Answer 3

It says you're a new contributor. Welcome to the community. Here are some tips on how to improve your code.

1. Don't abbreviate

While some accepted technical terms and established practices are abbreviated, such as HTML , CSS , and XHR , don't abbreviate words like students in your code. The practice of abbreviating comes from a time when computers had limited memory and screens were small, where you could only type something like maybe a hundred characters per line or something.

2. Use functions and name them well

I think what you're trying to do is get an input of students' names and grades, and get some statics on them, correct? If so, you can write your code as the following:

function getStudentNames() { /* write your code here */ }
function getStudentGrades() { /* write your code here */ }
function analyse(students, grades) { /* write your code here */ }
function renderResults(analysis) { /* write your code here */ }

// and then run the whole thing here:
function main() {
  var students = getStudentNames()
  var grades = getStudentGrades()
  var analysis = analyze(students, grade)
  renderResults(analysis)
}

With this structure in place we just have to worry about filling out the portion that says /* write your code here */ for each of the function. This is just one example of how you might want to structure your code. As you will later learn in your developer journey, this makes it easier to test later on.

Generally speaking, when you name a function, you want to name it in the following format: verbNoun() . For example, you might see functions like fetchData() , renderImage() , getShape() , etc. Sometimes you see functions that don't follow this, such as then() , or render() . In any case, don't use a noun as your function name.

3. Learn (more) array methods.

While using for-loop has some advantages, for most context, the performance boost is negligible and using array methods provides clarity and readability.

For instance, summing up an array of number can be achieved as follows:

var sum = [0,1,2,3,4].reduce(function(current, sum) {
  return current + sum
}, 0)

// more modern
const sum = [0,1,2,3,4].reduce((current, sum) => current + sum, 0)

console.log(sum) // prints 10

Helpful ones can be found at Mozilla Developers Network , which is generally an excellent source of learning anything web-related.

--

I hope this helps