javascript for every element in array code example

Example 1: For-each over an array in JavaScript

/** 1. Use forEach and related */
var a = ["a", "b", "c"];
a.forEach(function(entry) {
    console.log(entry);
});

/** 2. Use a simple for loop */
var index;
var a = ["a", "b", "c"];
for (index = 0; index < a.length; ++index) {
    console.log(a[index]);
}

/**3. Use for-in correctly*/
// `a` is a sparse array
var key;
var a = [];
a[0] = "a";
a[10] = "b";
a[10000] = "c";
for (key in a) {
    if (a.hasOwnProperty(key)  &&        // These checks are
        /^0$|^[1-9]\d*$/.test(key) &&    // explained
        key <= 4294967294                // below
        ) {
        console.log(a[key]);
    }
}

/** 4. Use for-of (use an iterator implicitly) (ES2015+) */
const a = ["a", "b", "c"];
for (const val of a) {
    console.log(val);
}

/** 5. Use an iterator explicitly (ES2015+) */
const a = ["a", "b", "c"];
const it = a.values();
let entry;
while (!(entry = it.next()).done) {
    console.log(entry.value);
}

Example 2: javascript every

const age= [2,7,12,17,21];
age.every(function(person){
return person>18;
});  //false

//es6
const age= [2,7,12,17,21];
age.every((person)=> person>18);  //false

Example 3: javascript every method

// array.every(function(elemnt)) method takes in a function 
// which evaulates each elment 
// The every method is designed to check if all the elements
// in an array meet a specific condition 
// This condition is defined within your function

let numbers = [1, 2, 3, 42, 3, 2, 4, -1];

let allPassed = numbers.every(function(element){
	return element > 0;
});

// This method returns a Boolean value
// allPassed is set to false because not all elements were greater than 0