I have string like as "1 + 2 - 3 + 10".
I want split it to "1", "+2", "-3", "+10".
Here is my code.
var expression = "1 + 2 - 3 + 10";
expression = expression.replace(/\s+/g, '');
let fields = expression.split(/([+-]\d+)/g);
console.log(fields);
But result is
["1", "+2", "", "-3", "", "+10", ""]
How can I make result ["1", "+2", "-3", "+10"]?
Your regular expression takes a group
/([+-]\d+)/
^ ^ group
which is included in the result set.
as result you get for each following iteration two parts, the part previous from the group and the group itself.
"1" first find
"+2" group as separator for splitting, included to result set
"" second find, empty because of the found next separator
"-3" second separator/group
"" third part without separator
"+10" third separator
"" rest part between separator and end of string
You could split with a positive lookahead of an operator.
const
string = '1 + 2 - 3 + 10',
result = string.replace(/\s+/g, '').split(/(?=[+-])/);
console.log(result);
I would handle this by first stripping off all whitespace, then using match() with the regex pattern [/*+-]?\d+, which will match all digits, with an optional leading operator (not present for the first term).
var input = "1 + 2 - 3 + 10";
var matches = input.replace(/\s+/g, '').match(/[/*+-]?\d+/g);
console.log(matches);
.match will return null if no matches are found. eg: null === 'a'.match(/b/):-)