In my code i need to write an if else block-
when the variable `currentValue` is holding only spaces -> certain code
But i don't know how to write this condition as currentValue can be a string of any size. It can hold " ", " " etc.
if i write currentValue!=" " it checks for single space.
Could look like
if( !currentValue.trim().length ) {
// only white-spaces
}
docs: trim
Even if its very self-explanatory; The string referenced by currentValue gets trimmed, which basically means all white-space characters at the beginning and the end will get removed. If the entire string consists of white-space characters, it gets cleaned up alltogether, that in turn means the length of the result is 0 and !0 will be true.
About performance, I compared this solution vs. the RegExp way from @mishik. As it turns out, .trim() is much faster in FireFox whereas RegExp seems way faster in Chrome.
Simply:
if (/^\s*$/.test(your_string)) {
// Only spaces
}
To match space only:
if (/^ *$/.test(your_string)) {
// Only spaces
}
Explanation: /^\s*$/ - match a beginning of a string, then any number of whitespaces (space, newline, tab, etc...), then end of string. /^ *$/ - same, but only for spaces.
If you do not want to match empty string: replace * with + to make sure that at least one character is present.
One can check if the string does not contain any non-whitespace characters with a regular expression. This method will only check each character at most once and will exit early as soon as it encounters a character that is not whitespace.
if(!/\S/.test(str)){
console.log('str contains only whitespace');
}
One could also use String#trim to remove all whitespace from the beginning and end of the string. If the string only contained whitespace, the result will be an empty string, which is falsy.
if(!str.trim()){
console.log('str contains only whitespace');
}
If the string might be null or undefined, the optional chaining operator can be used.
if(!str?.trim()){
console.log('str is null or undefined, or contains only whitespace');
}
try-:
your_string.split(" ").length
EDIT:
var your_string = " ";
var x = your_string.split(" ").length - 1;
if ( your_string.length > 0 && (your_string.length - x) == 0 ) {
alert("your_string has only spaces");
}
javascript match string.