A high-performance Python library that relies on nodejs to execute JavaScript

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Environments

Please note that you need to install Node.js and set up the NODE_PATH or NODE environment variable properly!
If not set, the default will use the Node.js in the system's path.

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Installation

pip install pyevaljs4

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Quickstart

import pyevaljs4

# example 1
rt = pyevaljs4.compile_("function f(a,b){console.log(a,b);return a+b;}")
res = rt.call('f', 'x', 'y')
print(res)
assert res == "xy"
# Another way of passing parameters
res = rt.call('f', arg_list=['x', 'y'])
print(res)
assert res == "xy"
# Other equivalent calling methods
print(rt.f('x',  'y'))
print(rt.f(arg_list=['x', 'y']))
# close runtime
rt.close()

# example 2
with pyevaljs4.compile_("function f(a,b){console.log(a,b);return a+b;}") as rt:
    res = rt.call('f', 'x', 'y')
    print(res)
    assert res == "xy"

# example 3
# empty context
rt = pyevaljs4.compile_()
# Add the function f to this context
rt.eval("function f(a,b){console.log(a,b);return a+b;}")
res = rt.call('f', 'x', 'y')
print(res)
assert res == 'xy'
# Other calling methods
res = rt.eval("f('x', 'y')")
print(res)
assert res == "xy"
rt.close()

# example 4
# Call JS asynchronous function
rt = pyevaljs4.compile_()
rt.eval("async function f(a,b){console.log(a,b);return a+b;}")
# To call the JS asynchronous function, you need to pass async_js_func=True
res = rt.call('f', 'x', 'y', async_js_func=True)
print(res)
assert res == "xy"
res = rt.f('x', 'y', async_js_func=True)
print(res)
assert res == "xy"
# The shortcut for calling the JS asynchronous function can only be used this way.
# other cases are not supported.
res = rt.eval('await f("x", "y")')
print(res)
assert res == "xy"
rt.close()

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Use a custom version of Node.js

• By setting environment variables to use a custom version of Node, you only need to set the NODE_PATH or NODE environment variables.

import os
# Highest priority
os.environ['NODE_PATH'] = '/path/to/node.exe'

# Second priority
os.environ['NODE'] = '/path/to/node.exe'