check if variable is undefined or null javascript code example

Example 1: javascript check if undefined or null

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

Example 2: check if variable is undefined or null jquery

if (variable == null) {
    // variable is either null or undefined
}

Example 3: 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 4: javascript check if undefined or null

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

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