如何在文件路径中使用变量？ - javascript，d3

Question

d3.tsv("//localhost/wordpress/" + my_var + ".tsv", function(d) {
d.frequency = +d.frequency;
return d;
}, function(error, data) {
if (error) throw error;

x.domain(data.map(function(d) { return d.letter; }));
y.domain([0, d3.max(data, function(d) { return d.frequency; })]);

I am trying to integrate the my_var variable successfully in the file path but it is not working. Can someone explain me why?

var my_var = <?php echo json_encode($title); ?>;

Answer 1

This

var my_var = <?php echo json_encode($title); ?>;

evaluates to:

var my_var = sometitle;

and sometitle is probably not defined. You want it to be a string:

var my_var = "<?php echo json_encode($title); ?>";

Answer 2

That is because my_var is not being treated as a placeholder for a string . Instead, my_var is being treated as a place holder for another variable named <?php echo json_encode($title); ?> <?php echo json_encode($title); ?> . Make the following change and everything should work:

var my_var = "<?php echo json_encode($title); ?>";

var url = "//localhost/wordpress/"
url += my_var
url += ".tsv"

d3.tsv( url, function(d) {
d.frequency = +d.frequency;
return d;
}, function(error, data) {
if (error) throw error;

x.domain(data.map(function(d) { return d.letter; }));
y.domain([0, d3.max(data, function(d) { return d.frequency; })]);