looping through the elements in a collection using a for-in loop

Question

looping through the elements in a collection using a for-in loop

Issue with IE 11 Console

Chrome Console Behavior

When changing the word 'item' to 'anotherItem' in the loop like so:

var obj = {
    id1: 'item 1',
    id2: 'item 2',
    id3: 'item 3'    
};
for (anotherItem in obj){
    console.log(anotherItem);
}

The loop runs smoothly

Questioning why IE 11 struggles with the keyword 'item'

javascript internet-explorer

Answer 1

Answer №1

item is defined as a built-in function in Internet Explorer, potentially read-only, which explains why you are unable to change its value.

Prior to the Edge browser, Microsoft was not consistent with following standards and included various features that deviated from standard practices. The item function is notably absent in Edge.

In addition, make sure you declare anotherItem before using it. Here's an example:

Try the following code snippet:

var obj = {
    id1: 'item 1',
    id2: 'item 2',
    id3: 'item 3'    
};

for (var anotherItem in obj){
    console.log(anotherItem);
}

If you fail to use the var keyword when declaring a variable and you're not operating in strict mode, it will be treated as a global variable unintentionally. Global variables act as properties on the global object, typically the window object in a web browser environment.

To prevent such errors, add the following line at the beginning of your JavaScript file to enforce strict mode:

"use strict";

You also have the option to apply strict mode only to specific functions like this:

(function() {
    "use strict";
    // code within this function is subject to strict mode
})()

Answer 2

item is defined as a built-in function in Internet Explorer, potentially read-only, which explains why you are unable to change its value.

Prior to the Edge browser, Microsoft was not consistent with following standards and included various features that deviated from standard practices. The item function is notably absent in Edge.

In addition, make sure you declare anotherItem before using it. Here's an example:

Try the following code snippet:

var obj = {
    id1: 'item 1',
    id2: 'item 2',
    id3: 'item 3'    
};

for (var anotherItem in obj){
    console.log(anotherItem);
}

If you fail to use the var keyword when declaring a variable and you're not operating in strict mode, it will be treated as a global variable unintentionally. Global variables act as properties on the global object, typically the window object in a web browser environment.

To prevent such errors, add the following line at the beginning of your JavaScript file to enforce strict mode:

"use strict";

You also have the option to apply strict mode only to specific functions like this:

(function() {
    "use strict";
    // code within this function is subject to strict mode
})()

Answer 3

Answer №2

Feel free to utilize this code snippet for outdated web browsers. Best of luck!

var fruits = ["apple", "orange", "cherry"];
fruits.forEach(myFunction);

function myFunction(item, index) {
   document.getElementById("demo").innerHTML += index + ":" + item + "<br>";
}

Answer 4

Feel free to utilize this code snippet for outdated web browsers. Best of luck!

var fruits = ["apple", "orange", "cherry"];
fruits.forEach(myFunction);

function myFunction(item, index) {
   document.getElementById("demo").innerHTML += index + ":" + item + "<br>";
}

looping through the elements in a collection using a for-in loop

Answer №1

Answer №2

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