如何替换javascript中的嵌套箭头功能以实现Safari兼容性？

Question

I am customizing a JavaScript visualization library and have written a small piece of code to fill an array for the hover info:

var text = zValues.map((zValues, i) => zValues.map((value, j) => {
  return ` ID: ${yValues[i]}<br> Tissue: ${xValues[j]}<br> Expression: ${value.toFixed(2)} ` 
 }))

It works for all browsers except Safari. I read that Safari does not support the arrow function, so I tried to replace this function as follows:

var text = zValues.map (function(zValues, i) { zValues.map (function (value, j) {
  return ` ID: ${yValues[i]}<br> Tissue: ${xValues[j]}<br> Expression: ${value.toFixed(2)} ` 
 });});

This does not give any error, but leads to an empty 'text' array. How can I fix the problem?

Answer 1

Arrow functions with just a single expression statement in the body have an implicit return. Functions created with function never have an implicit return (unless you count undefined I guess), so you need to explicitly return your arrow function expressions:

var text = zValues.map (function(zValues, i) { return zValues.map (function (value, j) {
  return ` ID: ${yValues[i]}<br> Tissue: ${xValues[j]}<br> Expression: ${value.toFixed(2)} ` 
 });});

(You already had the return on the innermost result expression.)