Remove empty or whitespace strings from array - Javascript

Question

I've found this beautiful method for removing empty strings - arr = arr.filter(Boolean).

But it doesn't seem to work on whitespace strings.

var arr = ['Apple', '  ', 'Mango', '', 'Banana', ' ', 'Strawberry']; arr = arr.filter(Boolean); // ["Apple", "  ", "Mango", "Banana", " ", "Strawberry"]  // should be ["Apple", "Mango", "Banana", "Strawberry"] 

Is there a nice way to expand this method to removing whitespaces as well or should i trim the whitespaces by iterating the array first?

Answer 1

filter works, but you need the right predicate function, which Boolean isn't (for this purpose):

// Example 1 - Using String#trim (added in ES2015, needs polyfilling in outdated // environments like IE) arr = arr.filter(function(entry) { return entry.trim() != ''; }); 

or

// Example 2 - Using a regular expression instead of String#trim arr = arr.filter(function(entry) { return /\S/.test(entry); }); 

(\S means "a non-whitespace character," so /\S/.test(...) checks if a string contains at least one non-whitespace char.)

or (perhaps a bit overboard and harder to read)

// Example 3 var rex = /\S/; arr = arr.filter(rex.test.bind(rex)); 

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With an ES2015 (aka ES6) arrow function, that's even more concise:

// Example 4 arr = arr.filter(entry => entry.trim() != ''); 

or

// Example 5 arr = arr.filter(entry => /\S/.test(entry)); 

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Live Examples -- The ES5 and earlier ones:

var arr = ['Apple', '  ', 'Mango', '', 'Banana', ' ', 'Strawberry']; console.log("Example 1: " + JSON.stringify(arr.filter(function(entry) { return entry.trim() != ''; }))); console.log("Example 2: " + JSON.stringify(arr.filter(function(entry) { return /\S/.test(entry); }))); var rex = /\S/; console.log("Example 3: " + JSON.stringify(arr.filter(rex.test.bind(rex))));

...and the ES2015 (ES6) ones (won't work if your browser doesn't support arrow functions yet):

var arr = ['Apple', '  ', 'Mango', '', 'Banana', ' ', 'Strawberry']; console.log("Example 4: " + JSON.stringify(arr.filter(entry => !entry.trim() == ''))); console.log("Example 5: " + JSON.stringify(arr.filter(entry => /\S/.test(entry))));