How to obtain the value of TR in JavaScript?

Question

How to obtain the value of TR in JavaScript?

Objective:
Extract the value "2TR" from "MARSSTANDGATA132TR" using JavaScript.
Need to determine the location of the digit 2 within the extracted string.

Issue:
Uncertain about the correct syntax to achieve this task.

Additional Details:
*The characters "TR" always appear at the end of the word.
*The digit "2" in "2TR" is individual and not part of a bigger number.
*Both the word and the address number vary.
*If the regex code fails to locate "TR" at the end of the word, the desired outcome cannot be retrieved.

function myFunction() {
    var str = "MARSSTANDGATA132TR"; 
    var n = str.search("TR");
    document.getElementById("demo").innerHTML = n;
}

<button onclick="myFunction()">Test</button>

<p id="demo"></p>

Appreciate your help!

javascript regex

Answer 1

Answer №1

To easily detect the characters "TR" at the end of a string, regex is not necessary.

You can simply check the last two symbols of the string; if they are "TR", then take the third symbol from the end - otherwise, handle any errors that may occur:

var str = "MARSSTANDGATA132TR";

if (str.slice(-2) == 'TR') {
  console.log(''+str.slice(-3, -2) + ' and index is ' + (str.length - 3));
} else {
  console.log('no TR');
}

Answer 2

To easily detect the characters "TR" at the end of a string, regex is not necessary.

You can simply check the last two symbols of the string; if they are "TR", then take the third symbol from the end - otherwise, handle any errors that may occur:

var str = "MARSSTANDGATA132TR";

if (str.slice(-2) == 'TR') {
  console.log(''+str.slice(-3, -2) + ' and index is ' + (str.length - 3));
} else {
  console.log('no TR');
}

Answer 3

Answer №2

Suppose you prefer using the index to locate the correct tr and num idx:

let str = "MARSSTANDGATA132TR"; 
let tr = str.search("TR"), numIdx;

if (tr !== -1) {
  numIdx = str[tr -1];      
  tr = str.substr(tr, tr + 1);
} else {
  alert('no TR');
}
console.log(tr);
console.log(numIdx)

If there are multiple instances of TR in the string, then ensuring that you have identified the right one is crucial.

let str = "MARSS**TR**ANDGATA132**TR**"; 
let trIdx = 0, tr, numIdx;

let findTrIdx = (str) => {
  let tmpIdx = str.search('TR');
  if (!parseInt(str[tmpIdx - 1])) {
    let newStr = str.substr(tmpIdx + 2, str.length -1);
    tmpIdx = tmpIdx + 2;
    findTrIdx(newStr);
  } 
  trIdx += tmpIdx;
  return trIdx;
}

trIdx = findTrIdx(str);

if (trIdx !== -1) {
    numIdx = str[trIdx -1];
  tr = str.substr(trIdx, trIdx + 1);
} else {
    alert('no TR');
}
console.log(tr);
console.log(numIdx)

Answer 4

Suppose you prefer using the index to locate the correct tr and num idx:

let str = "MARSSTANDGATA132TR"; 
let tr = str.search("TR"), numIdx;

if (tr !== -1) {
  numIdx = str[tr -1];      
  tr = str.substr(tr, tr + 1);
} else {
  alert('no TR');
}
console.log(tr);
console.log(numIdx)

If there are multiple instances of TR in the string, then ensuring that you have identified the right one is crucial.

let str = "MARSS**TR**ANDGATA132**TR**"; 
let trIdx = 0, tr, numIdx;

let findTrIdx = (str) => {
  let tmpIdx = str.search('TR');
  if (!parseInt(str[tmpIdx - 1])) {
    let newStr = str.substr(tmpIdx + 2, str.length -1);
    tmpIdx = tmpIdx + 2;
    findTrIdx(newStr);
  } 
  trIdx += tmpIdx;
  return trIdx;
}

trIdx = findTrIdx(str);

if (trIdx !== -1) {
    numIdx = str[trIdx -1];
  tr = str.substr(trIdx, trIdx + 1);
} else {
    alert('no TR');
}
console.log(tr);
console.log(numIdx)

How to obtain the value of TR in JavaScript?

Answer №1

Answer №2

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