d3.interpolateString()

d3.interpolateString(a, b)

Returns an interpolator between the two strings a and b. The string interpolator finds numbers embedded in a and b, where each number is of the form understood by JavaScript. A few examples of numbers that will be detected within a string: -1, 42, 3.14159, and 6.0221413e+23.

For each number embedded in b, the interpolator will attempt to find a corresponding number in a. If a corresponding number is found, a numeric interpolator is created using interpolateNumber. The remaining parts of the string b are used as a template: the static parts of the string b remain constant for the interpolation, with the interpolated numeric values embedded in the template.

For example, if a is "300 12px sans-serif", and b is "500 36px Comic-Sans", two embedded numbers are found. The remaining static parts of the string are a space between the two numbers (" "), and the suffix ("px Comic-Sans"). The result of the interpolator at t = 0.5 is "400 24px Comic-Sans".