JavaScript find string in array

The easiest way of doing that is just use indexOf method on our array of elements.

Practical example to detect if the element exists in our array:

// ONLINE-RUNNER:browser;

var elements = [
    "x",          // index: 0
    "y",          // index: 1
    "my_element", // index: 2
    "z",          // index: 3
];
var index = elements.indexOf("my_element");

if (index == -1) {
    console.log("Element doesn't exist");
} else {
    console.log("Element exists under index: " + index);
}

Additionaly we get index of this element in this array.

Flow:

var index = elements.indexOf("my_element");

• If the result index is -1 then the array doesn't contains the element we are looking for.
• If the index is any other then the element is under this index.

Practical function

We can also create practical function and enclose the logic:

// ONLINE-RUNNER:browser;

function arrayContains(array, element) {
    return (array.indexOf(element) > -1);
}

var elements = [
    "x",          // index: 0
    "y",          // index: 1
    "my_element", // index: 2
    "z",          // index: 3
];
console.log( arrayContains(elements, "my_element") );   // true
console.log( arrayContains(elements, "my_element_2") ); // false

Index of from specific index

We can also use indexOf to find element from some specific index in our array.

// ONLINE-RUNNER:browser;

var elements = [
    "x",          // index: 0
    "y",          // index: 1
    "my_element", // index: 2
    "z",          // index: 3
    "a",          // index: 4
    "my_element", // index: 5
    "b",          // index: 6
    "c"           // index: 7
];

// we start to find the string from the index 3 in our array
var index = elements.indexOf("my_element", 3);

if (index == -1) {
    console.log("Element doesn't exist");
} else {
    console.log("Element exists under index: " + index);
}