check if string contains uppercase javascript code example

Example 1: check if letter is uppercase javascript

const isUpperCase = (string) => /^[A-Z]*$/.test(string)

Example 2: regex for lowercase letters js

function hasLowerCase(str) {
    return (/[a-z]/.test(str));
}

Example 3: check if letter is uppercase javascript

isUpperCase('A') // true
isUpperCase('a') // false

Example 4: check if letter is uppercase javascript

var strings = 'this iS a TeSt 523 Now!';
var i=0;
var character='';
while (i <= strings.length){
    character = strings.charAt(i);
    if (!isNaN(character * 1)){
        alert('character is numeric');
    }else{
        if (character == character.toUpperCase()) {
            alert ('upper case true');
        }
        if (character == character.toLowerCase()){
            alert ('lower case true');
        }
    }
    i++;
}