how to check string is empty or not in ionic 4 code example

Example 1: check if string is number or not php

$var_num = "1";
$var_str = "Hello World";

var_dump( is_numeric($var_num), is_numeric($var_str) );

/* 
Output -
 bool(true)
 bool(false)
*/

Example 2: coldfusion check if key exists and not empty

<cfset arrayOfStructs = deserializeJson(jsonJobsOpen)>
<cfloop array="#arrayOfStructs#" index="thisValue">
    <!--- Now you can use this condition to check for empty values --->
    <cfif StructKeyExists(thisValue, "JOBID") and Len(thisValue.JOBID) GT 0>
    ... 
</cfloop>