replace number between two tags javascript

Question

var input = " <root> <date>1995-03-03</date> <heure>13:33</heure> <day0>2</day0> <day1>0</day1> <day2>0</day2> <no2>1</no2> <pm10>2</pm10> <day0_o3>0</day0_o3> <day1_o3>0</day1_o3> <day2_o3>0</day2_o3> </root>"

Suppose i want to update day0 value as 6, then output will be

OutPut = " <root> <date>1995-03-03</date> <heure>13:33</heure> <day0>6</day0> <day1>0</day1> <day2>0</day2> <no2>1</no2> <pm10>2</pm10> <day0_o3>0</day0_o3> <day1_o3>0</day1_o3> <day2_o3>0</day2_o3> </root>"

Thanks for the response i have fixed this

input.replace(/<day0>.*<\/day0>/, '<day0>6</day0>');

Answer 1

im not sure how you get the input but if its from the DOM, you can use document.getElementsByTagName("day0")[0].innerText = "new output";

please give a bit more details if you meant something else

Answer 2

Using pure javascript you can write something like this:

document.querySelector("day0").textContent = "6";

If you should support browsers, that do now know about textContent, you can write:

document.querySelector("day0").innerText = "6";

Do not use innerHTML to replace text to prevent XSS vulnerability.

Answer 3

You could also write your own little function to look for the tags in the string, assuming the input will always be a string with tags in it.

for example:

var replaceValueInTag = (tags, tagName, newValue) => {
    var startTag = `<${tagName}>`;
    var endTag = `</${tagName}>`;

    var indexOfStartTag = tags.indexOf(startTag);
    var indexOfEndTag = tags.indexOf(endTag);

    var value = tags.substring(indexOfStartTag + startTag.length, indexOfEndTag);

    return tags.replace(`${startTag}${value}${endTag}`, `${startTag}${newValue}${endTag}`); 
}

var tags = " <root> <date>1995-03-03</date> <heure>13:33</heure> <day0>2</day0> <day1>0</day1> <day2>0</day2> <no2>1</no2> <pm10>2</pm10> <day0_o3>0</day0_o3> <day1_o3>0</day1_o3> <day2_o3>0</day2_o3> </root>":

replaceValueInTag(tags, 'day0', '6');

// output: 
// <root> <date>1995-03-03</date> <heure>13:33</heure> <day0>6</day0> <day1>0</day1> <day2>0</day2> <no2>1</no2> <pm10>2</pm10> <day0_o3>0</day0_o3> <day1_o3>0</day1_o3> <day2_o3>0</day2_o3> </root>