Javascript parameter is not defined - Stack Overflow

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So I try to make a collection of buttons, which print out a hello and the name of the button. The code below doesn't work because "Uncaught ReferenceError: Mike is not defined". Its a parameter, how do I even define it?

<input type="button" value="Say hello to Mike" onClick="hello(Mike);" />

and the JS is something like this:

function hello(name) {
... }

I have another button where clicking doesnt send any parameters and it works just as intended.

edit: Putting Mike in quotations produces another error: "Uncaught SyntaxError: missing ) after argument list". I am doing this as a homework and we are required to write the html with javascript, below is my modified, whole line of code which is throwing the error.

 document.write('<input type="button" value="Say hello to Mike" onClick="hello('Mike');" />');

could the document.type be the cause of the problem? Between these 2 errors, I do literally nothing else than add the quotation marks in the code.

edit2: It finally worked after I added \ before the quotation marks.

So I try to make a collection of buttons, which print out a hello and the name of the button. The code below doesn't work because "Uncaught ReferenceError: Mike is not defined". Its a parameter, how do I even define it?

<input type="button" value="Say hello to Mike" onClick="hello(Mike);" />

and the JS is something like this:

function hello(name) {
... }

I have another button where clicking doesnt send any parameters and it works just as intended.

edit: Putting Mike in quotations produces another error: "Uncaught SyntaxError: missing ) after argument list". I am doing this as a homework and we are required to write the html with javascript, below is my modified, whole line of code which is throwing the error.

 document.write('<input type="button" value="Say hello to Mike" onClick="hello('Mike');" />');

could the document.type be the cause of the problem? Between these 2 errors, I do literally nothing else than add the quotation marks in the code.

edit2: It finally worked after I added \ before the quotation marks.

• javascript

Share Improve this question Follow edited Mar 25, 2017 at 7:25 Codereerer asked Mar 25, 2017 at 6:39 CodereererCodereerer 3311 gold badge11 silver badge55 bronze badges 5

• Put single quotes around Mike, if it's to be parsed as a literal. – cartant Commented Mar 25, 2017 at 6:40
• Put Mike in single quotes – Shinigami Commented Mar 25, 2017 at 6:41
• As is apparent by the syntax coloring your string does not include Mike. To use the ' character in a string bounded by the same character you need to escape it i.e. ... hello(\'Mike\')... – Kiren Commented Mar 25, 2017 at 7:13
• Try this document.write('<input type="button" value="Say hello to Mike" onClick="hello(\'Mike\');" />'); – Vishal Commented Mar 25, 2017 at 7:13
• Vishal: that works. Goddamn, what a stupid error.. Thanks everyone! – Codereerer Commented Mar 25, 2017 at 7:22

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3 Answers 3

Sorted by: Reset to default 4

Since Mike is a string, correct syntax would be

onClick="hello('Mike');"

Since there are no quotes, javascript treating that as a variable.

Declare as a String in Mike .In your code The mike act like a variable .So the java-script check this variable defined or not. So only Its throw the Mike is undefined.

function hello(name) {
console.log(name)
}

<input type="button" value="Say hello to Mike" onClick="hello('Mike');" />

when you user the function hello,param 'Mike' error, the correct writer:

you write this,system think it's a variable

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