javascript check if string is empty code example

Example 1: javascript regex check if string is empty

function IsEmptyOrWhiteSpace(str) {
    return (str.match(/^\s*$/) || []).length > 0;
}

Example 2: javascript check if null

if (variable === null) { //Executes only if variable is null but not undefined
  //Code here
}

if (variable == null) { //Executes if variable is null OR undefined
  //Code here
}

Example 3: js if string not empty

if (!str.length) { ...

Example 4: javascript check for null variables

var myVar=null;

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

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

Example 5: 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
}

Example 6: javascript check if undefined or null or empty string

// simple check do the job
if (myString) {
 // comes here either myString is not null,
 // or myString is not undefined,
 // or myString is not '' (empty).
}