JS to determine whether the string is empty, filter the space, find the string position, and so on set of functions

This is an online collection of JS code snippet, used to determine whether the specified string is empty, filter the space on either side of a character in a string, find where the specified string starts, use the Isfloat function to determine whether a string consists of a number (int or long or float), The Isdigital function determines whether a string is composed of a number (int or long), and so on:

//The IsEmpty function determines whether a string is emptyfunctionIsEmpty (HIS) {flag=true; for(vari=0;i){if(His.charat (i)! = "") {flag=false;  Break;}}returnFlag;}//trim function to remove spaces on both sides of a stringfunctionTrim (HIS) {//Find string start positionPos_start =-1; for(vari=0;i){if(His.charat (i)! = "") {Pos_start=i; Break; }}//Find string End positionPos_end =-1; for(vari=his.length-1;i>=0;i--){if(His.charat (i)! = "") {Pos_end=i; Break; }}//the returned stringStr_return = ""if(Pos_start!=-1 && Pos_end!=-1){  for(vari=pos_start;i<=pos_end;i++) {Str_return= Str_return +His.charat (i);}}returnStr_return;} //The Isdigital function determines whether a string consists of a number (int or long)functionisdigital (str) { for(ilen=0;ilen<str.length;ilen++){if(Str.charat (Ilen) < ' 0 ' | | str.charat (ilen) > ' 9 ' ){return false;} }return true;}//The Isfloat function determines whether a string consists of a number (int or long or float)functionisfloat (str) {Flag_dec= 0 for(ilen=0;ilen<str.length;ilen++){if(Str.charat (ilen) = = '. ') {Flag_dec++;if(Flag_dec > 1)return false;ElseContinue;} if(Str.charat (Ilen) < ' 0 ' | | str.charat (ilen) > ' 9 ' ){return false;} }return true;}

JS to determine whether the string is empty, filter the space, find the string position, and so on set of functions