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Helllo, I'm having a div like this:
<div>1+1</div>
How can I get these '1+1' to the javascript and calculate them to '2'?
Thanks in advance!
you can use innerHTML property of element by javascript to extract the value:
document.getElementById("div").innerHTML
and then use eval() method to evaluate the math expression:
var exp=document.getElementById("div").innerHTML;
alert(eval(exp));
You need to somehow identify this div, e.g
<div id="div-with-expression">1+1</div>
And code will be like:
console.log(eval(document.getElementById('div-with-expression').innerText));
You can use eval:
var equation = getElementById(IdOfDiv).innerHTML;
var result = eval(equation);
Well, You could use the Javascript eval() func:
http://www.w3schools.com/jsref/jsref_eval.asp
But, eval functions can introduce malicious code into your environment.
I'm not sure as to what your purpose to start with and what your assumptions are for that input but here's another way to go about it with regex although it's more complicated:
var myRegexp = /(\d+)(\+)(\d+)/;
var match = myRegexp.exec("1+1");
// parseInt(match[0]) == 1 ,as an Int
// match[1] = '+', you could figure what operand this is with 'if else' conditions
// parseInt(match[2]) == 1 ,as an Int
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I’ve been trying to do find if a variable contains a digit inside of it. And for some reason, I put (exp.) ‘Majorpassword09’ and it just prints a false?
// vars
var regex = new RegExp(‘.*\d.*’)
var str = ‘Scorpio08’
// main
function reg1() {
if (regex.test(str)){
console.log(‘true’);
}else{
console.log(‘false’);
}
}
reg1();
EDIT: I’ve put the title as Incorrect regex expression because that's the only thing that I think is wrong.
You're most likely on a mac.
Your code shows that you're using fancy quotes. Like these ones: ‘’. You need to use normal quotes, like ', and ".
Here's a solution to your problem.
// vars
var regex = new RegExp(".*\\d.*")
var str = "Scorpio08"
// main
function reg1() {
if (regex.test(str))
{
console.log("true");
}else{
console.log("false");
}
}
reg1();
Whatever text editor you're using, it has fancy quotes on. Consider looking in the settings, or on Google, to find out how to disable them.
as you are using string to create a RegExp Object thus have to use two backslashes to properly escape
var regex = new RegExp(‘.*\\d.*’)
or
var regex = /.*\d.*/
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Is there a way to access all the object instances starting with a common string.
Example: I have instances named button64, button223, button856471, button229846, etc. I have no control over how these instances are named. I want to push all these in an array.
I am not creating these objects, I just have to write a javascript which sits in this HTML page and collects all the object instances starting with the string 'button'.
The purpose is to reach out to a desired object out of these and change the visual element.
Also, the solution has to be compatible with IE8. Any ideas about how should I iterate?
If you can use jQuery, you could write:
var buttonsArray = [];
$("div").each(function() {
var id = $(this).attr("id");
if (id && id.indexOf("button") == 0) {
buttonsArray.push($(this));
}
});
You can use regular expressions to find any expression matching the pattern. Using the match method, every instance of the pattern is returned as an array.
var str = document.getElementById("sample");
var arr = string.match(/button[\d]*/g);
The regular expression on line two will match any result that has "button" and will stop once it encounters a character afterwards that is not a digit.
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In javascript, I have a large string like
str="a lot of lines\n"
str+="foo\n"
str+="the stuff I want\n"
str+="bar and a lot more stuff\n"
How do I put just the part:
the stuff I want
between "foo" and "bar" into a new string variable?
Depending on where exactly 'the stuff you want' is in the string you can do a similar approach to this one:
var str="a lot of lines\n";
str+="foo\n";
str+="the stuff I want\n";
str+="bar and a lot more stuff\n";
var stuff = str.split('\n')[2]; // the stuff i want
EDIT:
If you want the stuff between foo and bar, then you can do something like:
var stuff = str.match(/foo((.|\n)*)bar/)[1]; // contains newlines!
var str = "a lot of lines foo the stuff I want bar and a lot more stuff"
str.substring(str.indexOf("foo")+3,str.indexOf("bar") )
var str="a lot of lines\n";
str+="foo\n";
str+="the stuff I want\n";
str+="bar and a lot more stuff\n";
// ------------------------------
var myRegex = /foo(.*)bar/;
if (myRegex.test(str)) {
alert(myRegex[0]);
}
With a regex, it should do the trick.
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Writing a function in JavaScript. The plan is the function creates an object, which requires boolean statements as parameters. Something like this ->
var foo = new fuzz("pie < squirrel", "monkey === banana");
My question is - Is this evil?
*Note - * Inside the function 'fuzz' I will run checks on the values of the parameters. (Check string.length etc). I think this is how one is meant to use eval, it just has such a bad reputation on t'up web.
Thanks
Summing up the conclusions in the comments: write a simple rule evaluation engine! E.g.:
var variables = { ... };
function niceEval(condition) {
var operands = condition.match(/(\w+)\s+(\S+)\s+(\w+)/);
switch (operands[2]) {
case '<' :
return variables[operands[1]] < variables[operands[3]];
...
}
}
This also gives you a lot more control over possibly occurring errors than blindly evaling a string.
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Here's my function:
CSS_Left = '450px';
CSS_Left.replace('px', '');
alert(CSS_Left);
It returns '450px'
Here's an example:
http://jsfiddle.net/D2Mgb/
I want it to replace 'px' with nothing.
In JavaScript, Strings are immutable.
All types except objects define immutable values. Specifically, strings are immutable (unlike in C for instance).
So, str.replace returns a new string. Try this instead:
CSS_Left = CSS_Left.replace('px', '');
Or if you don't want to overwrite the original string, just do it in the alert call
alert(CSS_Left.replace('px', ''));
It's worth noting that .replace can also take a regexp. Though it's not necessary in your case, you could do something like this to achieve the same result
CSS_Left = CSS_left.replace(/px$/, '');
Because .replace() return a new string. If you want to update the old string you should write:
CSS_Left = CSS_Left.replace('px', '');
I am not sure, but the function replace() creates a new variable.
Try this :
var CSS_Left = '450px';
CSS_Left = CSS_Left.replace('px', '');
alert(CSS_Left);
The output of the replace call needs to be reassigned to CSS_Left