[Solved-5 Solutions] Check for an empty string in javascript - javascript tutorial
Problem:
Check for an empty string in javascript
Solution 1:
If we need to check whether there's any value, we can do
if (strValue)
{
//....
}
If we want to check specifically for an empty string over null, We would think checking against "" is our best bet, using the === operator.
if (strValue === "")
{
//...
}
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Checking if a Key exist in a JavascriptSolution 2:
To check whether a string is empty, null or undefined we can use:
function isEmpty(str)
{
return (!str || 0 === str.length);
}
To check whether a string is blank, null or undefined we can use:
function isBlank(str)
{
return (!str || /^\s*$/.test(str));
}
To check whether a string is blank or contains only white-space:
String.prototype.isEmpty = function()
{
return (this.length === 0 || !this.trim());
};
Solution 3:
We can use !!(not not) operator.
if(!!str)
{
//......
}
or use type casting:
if(Boolean(str))
{
//......
}
- Both do the same function, type cast the variable to boolean, where str is a variable.
- Returns false for null,undefined,0,000,"",false.
- Returns true for string "0" and whitespace " ".
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Convert string to Boolean in JavascriptSolution 4:
If we want to ensure that the string is not just a group of empty spaces (In our imagining this is for form validation) we need to do a replace on the spaces.
if(str.replace(/\s/g,"") == "")
{
//......
}
Solution 5:
In this solution to check for an str.Empty,
if (!str.length)
{
//...
}