Using regex:
var str = "my car is red";
var stringArray = str.split(/(s+)/);
console.log(stringArray); // ["my", " ", "car", " ", "is", " ", "red"]
s
matches any character that is a whitespace, adding the plus makes it greedy, matching a group starting with characters and ending with whitespace, and the next group starts when there is a character after the whitespace etc.
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