this is my input string in react : 4- 3-4 I want to check onChange() function when a duplicate arithmetic entered, like this - replace last operator with first one, how can i detect that on change function? input should change on change to 4 3-4 I tried and tested but failed This is my regex for finding operators and last operator /[ *\/-]/g /[ *\/-]$/g

CodePudding user response：

You may try a regex replace approach:

var input = "4- 3-4";
var output = input.replace(/[*/ -] ([*/ -])/g, "$1");
console.log(output);

This approaches matches two or more successive arithmetic operators, capturing the final one. It then replaces with just this final operator.

CodePudding user response：

let input1 = "4- 3-4";
let input2 = "4  3-4"
let output1 = input1.replace(/[ *\/-] ([ *\/-])/g, "$1");
let output2 = input2.replace(/[ *\/-] ([ *\/-])/g, "$1");
console.log(output1);
console.log(output2);