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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects The Student Record Search Challenge Solution

fredyrosales
fredyrosales
10,572 Points
Posted by fredyrosales
fredyrosales
10,572 Points

Need a brief overview.

Guys i know we went over this a while back but i can't quit understand this line of code anymore. It would be much appreciated if someone can explain it for me, Thank You! for (var i = 0; i < students.length; i += 1) { student = students[i];

Daniel Springer
Daniel Springer
7,600 Points

hey it seems that what your dealing with there is whats called a for loop. Let me try to explain it out in plain english lol.

so you have a variable in your loop (i) that youve assigned a value of zero. you have told js that for each time that i is less than students.length (the number of objects in your array) run the code in the brackets {} and than when you are done running that code increment the variable i by 1.

so if you had 8 people in your students array. the code would run 8 times. stopping the moment that i is no longer smaller than the students.length.

Hope the explanation helps ^_^

2 Answers

Matt Milburn
Matt Milburn
20,786 Points
Matt Milburn
Matt Milburn
20,786 Points

Hi Fredy,

So let's break this down...

// Here we have an array (or list) of 4 student names
var students = ['Matt', 'John', 'Mary', 'Jane'];

// Now we are going to "loop" through the `students` array...
//   1. var i = 0             // create a counter variable called `i` (aka "iteration")
//   2. i < students.length   // run this loop as long as this condition is true
//   3. i += 1                // increment `i` at the end of every loop iteration
for (var i = 0; i < students.length; i += 1) {
    // Use "bracket notation" to access the student at the array index of `i` (aka "position")
    var student = students[i];

    // Let's also print this to the page with a line break after `<br>` each student
    document.write(i + ': student + '<br>');
}

This will output the following HTML to the page...

0: Matt<br>
1: John<br>
2: Mary<br>
3: Jane<br>
Vance Rivera
Vance Rivera
18,322 Points
Vance Rivera
Vance Rivera
18,322 Points

The for loop loops through a block of code for a specified number of times.

//var i = 0
//var i : is the variable that will be your index variable for students starting at 0 which is the first student

//i < students.length
//condition that will determine how many times to run the block of code inside the loop
//while var i is less then students array length run this code block

//i += 1
//each time the code block is executed increment var i by 1
//this allows us to target the next student in the students array and execute the code in the loop per student
for(var i = 0; i < students.length; i += 1){

  var student = students[i];
  ///code to run for each loop with new student
}

hope this helps. Cheers!