JavaScript error handling special characters †

Question

In a textarea, I want to determine the position of the last "†" character. vartextField=document.getElementById("main_field");console.log(textField.value.indexOf("†"));<textareaid="main_field">Text†enteredbyuser

P粉043432210 · Answer

First, let's see how it works.

console.log(document.getElementById("textField1").value.lastIndexOf("†"));
console.log(document.getElementById("textField2").value.lastIndexOf("†"));


a†b†c†d

Now that we've seen this, we need to find out what's wrong with your code. First, you need to check if textField.value contains the characters you are searching for. Next, look at this call in the code:

.substring(0, startPos)

This actually gets the substring starting from the beginning up to startPos. Judging from the name of startPos, it seems that instead of getting the string from before startPos, it gets it from startPos.