How do NOT differentiate upper and lower case with index?

Question

I have the following function:

var name = $(".infoname").text();
if(name.indexOf("Carro")!=-1) {
    alert("existe");
} else {
    alert("não existe");
}

How can I make for the indexOf do not differentiate capital or minuscule, example "Carro", "carro".

Answer 1

Make the contents of your variable name and the parameter of indexOf uppercase or lower case.

Capital

// Exemplo em maiúsculo
if(name.toUpperCase().indexOf("CARRO") !== -1) {
    alert("existe");
} else {
    alert("não existe");
}

Tiny

// Exemplo em minúsculo
if(name.toLowerCase().indexOf("carro") !== -1) {
    alert("existe");
} else {
    alert("não existe");
}

Answer 2

Why doesn’t it work?

The following example defines two string variables. The variables contain the same string, except that the second string has uppercase letters. The first method log has 19. However, as the method indexOf is sensitive to box, the string "cheddar" is not found in myCapString, therefore the second method log displays -1.

var myString    = "brie, pepper jack, cheddar";
var myCapString = "Brie, Pepper Jack, Cheddar";

console.log('myString.indexOf("cheddar") é ' + myString.indexOf("cheddar"));    
// Exibe 19
console.log('myCapString.indexOf("cheddar") é ' + myCapString.indexOf("cheddar")); 
// Exibe -1

Source: String.prototype.indexof()

---

Alternative #1:

Force down box in his string:

var name = 'CaRrO';
if(name.toLowerCase().indexOf("Carro".toLowerCase())!=-1) {
    alert("existe");
} else {
    alert("não existe");
}

Note that both the string as to the searchValue were in low box, which helps a lot in the dynamics.

---

Alternative #2:

Further improving the dynamics, you can create a function for this.

Take my example:

function in_str(string, value) {
    string = string.toLowerCase();
    value = value.toLowerCase();

    if (string.indexOf(value) != -1)
        return true;
    else
        return false;
}

console.log(
    in_str('Carro', 'Carro'), // true
    in_str('carro', 'CARRO'), // true
    in_str('caRRo', 'carro'), // true
    in_str('carro', 'caRRo'), // true
    in_str('MoTo', 'caRRo'), // false
    in_str('o Carro furou o pneu', 'caRRo') // true
);

---

Alternative #3:

The one I consider the best way and with even more dynamic, is to define a prototype to the class String. Hence the use will be identical to the .indexOf (except by the name of the method).

Take my example:

String.prototype.indexOfCaseIns = function(searchValue, fromIndex) {
    return this.toLowerCase().indexOf(searchValue.toLowerCase(), fromIndex);
}

var str = 'Olá mundo!';

console.log(
    str.indexOfCaseIns('MunDO'), // 4
    str.indexOfCaseIns('world'), // -1
    str.indexOfCaseIns('Olá'), // 0
    str.indexOfCaseIns('ola'), // -1
    str.indexOfCaseIns('OLá'), // 0
    str.indexOfCaseIns('á munD'), // 2
    str.indexOfCaseIns('undo!') // 5
);

Notice that it follows the same sense of indexOf: returns -1 if not found or the index number of the searched value.

---

Applying in your code:

var name = $(".infoname").text();
if(name.indexOfCaseIns("Carro")!=-1) { // só trocar o método ;D
    alert("existe");
} else {
    alert("não existe");
}

Answer 3

A simpler form that avoids indexOf, toLowerCase and toUpperCase is to use regular expression.

var name = $(".infoname").text();
if(name.match(/carro/i))) {
    alert("existe");
} else {
    alert("não existe");
}

This will work if the string contains Carro, carro or contains nothing.

Complete example with all possibilities:

const str1 = "carro minusculo"
if (str1.match(/carro/i)) {
    console.log("existe")
} else {
    console.log("nao existe")
}

const str2 = "Carro maiúsculo"
if (str2.match(/carro/i)) {
    console.log("existe")
} else {
    console.log("nao existe")
}

const str3 = "sem"
if (str3.match(/carro/i)) {
    console.log("existe")
} else {
    console.log("nao existe")
}