Foreach javascript object array code example

Example 1: javascript foreach object

const list = {
  key: "value",
  name: "lauren",
  email: "[email protected]",
  age: 30
};

// Object.keys returns an array of the keys
// for the object passed in as an argument.

Object.keys(list).forEach(val => {
  let key = val;
  let value = list[val];
  console.log(`${key} : ${value}`);
});

// Returns:
// "key : value"
// "name : lauren";
// "email : [email protected]"
// "age : 30"

Example 2: javascript foreach index

users.forEach((user, index)=>{
	console.log(index); // Prints the index at which the loop is currently at
});

Example 3: foreach jas

const array1 = ['a', 'b', 'c'];

array1.forEach(element => console.log(element));

Example 4: forEach

const arraySparse = [1,3,,7]
let numCallbackRuns = 0

arraySparse.forEach((element) => {
  console.log(element)
  numCallbackRuns++
})

console.log("numCallbackRuns: ", numCallbackRuns)

// 1
// 3
// 7
// numCallbackRuns: 3
// comment: as you can see the missing value between 3 and 7 didn't invoke callback function.

Example 5: javascript foreach in object

for (var key in validation_messages) {
    // skip loop if the property is from prototype
    if (!validation_messages.hasOwnProperty(key)) continue;

    var obj = validation_messages[key];
    for (var prop in obj) {
        // skip loop if the property is from prototype
        if (!obj.hasOwnProperty(prop)) continue;

        // your code
        alert(prop + " = " + obj[prop]);
    }
}