Answers for "javascript if null or empty string"

javascript if string empty

// Test whether strValue is empty or is None
if (strValue) {
    //do something
}
// Test wheter strValue is empty, but not None 
if (strValue === "") {
    //do something
}

javascript null or empty

var myVar=null;

if(myVar === null){
    //I am null;
}

if (typeof myVar === 'undefined'){
    //myVar is undefined
}

javascript validate if string null undefined empty

/**
  * Checks the string if undefined, null, not typeof string, empty or space(s)
  * @param {any} str string to be evaluated
  * @returns {boolean} the evaluated result
*/
function isStringNullOrWhiteSpace(str) {
    return str === undefined || str === null
                             || typeof str !== 'string'
                             || str.match(/^ *$/) !== null;
}